Mark Schatzker tested the latestand supposedly, greatestof them in Rome.

There are two types of people in the world: Those who have heard of augmented reality and those who haven't. The latter group is largein the billions, I imaginebut shrinking exponentially. Up until a moment ago, you may have been a part of it, but you're not anymore.

Augmented reality, or AR, promises to change the very nature of travel forever: Never again will you struggle to find the Leaning Tower of Pisa, Smithfield's Market, or that charming little bistro in a hidden corner of the second arrondissement. Instead, you'll pull out your smartphone, launch an AR app, and view the world around you on the phone's screen (just as you do when you take a picture). In an instant, your smartphone trades data with the Internet and GPS satellites, and it suddenly knows a very important fact that you do not: There's an even better bistro much closer to where you're standing. Your phone tells you so, by way of a little flag or text bubble, when you point it in the right direction.

But wait, there's more!

With a simple tap on the screen, you can phone that bistro and make a reservation. Then you can switch to Map View and follow the arrows as they lead you all the way there. When you arrive, if a phrase on the menu like os á moelle au sel de Guérande, toasts grillés confuses you, no problem. Snap it with your smartphone and, in seconds, the translation"bone marrow with Guérande salt served on toast"will arrive, along with the recipe. If the sommelier's pick seems overpriced, snap the label and in seconds you'll receive price comparisonsand expert tasting notes, too. After dinner, if you're in the mood for some live music, get out your smartphone and look at a map of Paris that shows who's playing where. Or, better yet, see what bands locals are tweeting about.

In other words, never feel like a naive out-of-towner again. Thanks to augmented reality and a spate of new apps including Wikitude, Nearest Tweets, and Google Goggles, the innumerable little hurdles that can trip up your travelsordering a meal, getting directions, picking a good restaurant, finding the best shopshave all been cleared in one amazing high-tech leap.

Or least that's what the app developers will have you believe. But can a $5 or $10 app really make visiting cities like Paris, Tokyo, or Moscow a breeze? To find out, I flew to Rome carrying an iPhone 4 and a Samsung Captivate, which runs Google's Android operating system. After three days of rigorous testingduring which I walked more than 25 miles, weaved past several thousand tourists, consumed two excellent bowls of pasta and molti cones of gelato, and downloaded over 100 megabytes of dataI had the answer. So, does AR deliver all that it promises? Not so much.

Here's what augmented reality is actually like:

You're walking from your hotel to the Colosseum. Google Maps, which isn't exactly new, shows you the way. So far so good. As you walk, you look down a side street and notice a handsome building in the distance with an ornate white statue on the roof. What is it? You switch from Google Maps to Google Goggles, a new app that can analyze a photo of almost anythinghistoric site, wine bottle, paintingand tell you what it is. You snap the building and Google Goggles begins its analysis. A moment later, it delivers its response: "No close image matches found."

Not to worryyou have other options. You open an app called Nearest Wiki, found on the Acrossair browser, which you've already downloaded. Nearest Wiki combines GPS technology and the Internet to match Wikipedia entries with their actual geographic locations. You hold your smartphone up andright before your eyesreality becomes augmented. There is a box floating next to the ornate building. It says, "Santi Marcellino e Pietro."

Elated, you marvel at the wonders mankind hath wrought (and you haven't even seen the Colosseum yet), then tap the Santi Marcellino e Pietro box. Then you wait. You wait a painfully long time. Then you wait some more. After perhaps two minutesa geologic epoch when you're standing on a street in Rome, trying to get to the Colosseuma picture of a building finally appears. Lo, it is the wrong building. So you click the Back button and endure another glacial pause. Finally, Nearest Wiki throws up its hands and quits. The mystery building, you tell yourself, is one aspect of reality that shall remain unaugmented.

Later, you round a corner and the Colosseum comes breathtakingly into view. You launch Google Goggles and take a snap. Goggles recognizes the ancient monument in seconds. Its top search result is a blog called "The Vatican and Coliseum." You begin reading. The blog is so boring that one of the world's greatest masterpieces of engineering now seems mundane. This nevertheless qualifies as one of Google Goggles's better moments. A little farther on, Google Goggles recognizes the Arco di Constantino, or Arch of Constantine, but this time its top result is a Web site promoting pre-paid cards for the U.S.-based ARCO gas station chain. (Google Goggles also failed to translate a single menu entry and choked on every wine label.)

Still not out of options, you open another app, a $6 travel guide to Rome put out by a Montreal-based company called mTrips. About the Arch of Constantine, a 1,700-year-old monument that has inspired at least one book, it has a whopping 24 words of description and concludes, incredibly, with a link to the Wikipedia write-upwhich, as I hardly need remind you, is free.

Wikipedia shows up rather a lot in travel appseven in paid apps like mTrips and Tripwolf. Craving somethinganythingother than repackaged Wikipedia, I launched a program called Nearest Tweets, an AR app that shows you the tweets of nearby Twitter users. What, I wondered, were locals tweeting about? I was about to have unfettered access to the secret life of actual Romans. I envisioned foodies tweeting about where to get the best spaghetti all'amatriciana, or perhaps an insider tip on an undiscovered menswear designer. What I got was yet another egregious wait. Eventually, the app launched and I did a 360-degree pan around Rome. A solitary tweet appeared (by one @ivagabondo), and it read as follows: "The Cranberries–'Just My Imagination'" and was followed by a link to a YouTube video. Profound.

Long before smartphones, the task of augmenting the traveler's reality fell to guidebooks, and for more than two centuries, some of them did an excellent job. Smartphones, however, can do things books cannot. They're smaller but can hold far more information. Their maps, which are always up to date, can point out where you are, where you're going, and the best way to get there on foot. Smartphones can present text, full-color photos, videos, and audio. Oh, and you can use them as phones.

The problem is that we are in the early, heady days of travel apps and AR. It's three seconds after the big bang, metaphorically speaking, and the universe is still jumbled and chaotic. Augmented reality's biggest wow featurenamely, superimposing information over whatever you're looking at on the screenbasically sucks. The screen jiggles, text bubbles crowd each other out, and the information is superficial. Your arms soon tire, your eyes strain. It's like trying to thread a needle while jogging down a dirt path.

Most apps make the same mistake: too much information. Consider Trasteverywhere, which celebrates the Trastevere neighborhood. Its tagline, "Find everything in Trastevere," couldn't be more accurate. One afternoon, I searched "shopping," "handcrafts," and "restaurants and pizzerias" in a half-mile radius. Trasteverywhere returned 69 points of interest. Each took a painfully long time to load (some just didn't load, period), and the vast majority were of zero interest. In 20 minutes of squinty-eyed tapping and reading, I found a single appealing listing, for a botanic garden. Alas, it was closed.

Even if it hadn't been, would it have been worth the wait? No way. Instead of taking in the beauty of Rome, I was doing what I do all too often at work: staring at a computer screen. Like so many smartphone and AR apps, Trasteverywhere aggregates information but doesn't filter it.

There is reason to be hopeful, however. The mTrips guide to Rome may have its faultsforemost among them inane descriptions repurposed from Marco Polo guides and Wikipediabut it does boast one eminently usable feature: an itinerary generator. You enter the dates of your visit and your accommodations, and then rate your preferences among museums, monuments, parks, and "religious," andpresto!mTrips creates an itinerary. It doesn't yet incorporate restaurants and shopping, but mTrips takes you to see things you will like. Will it be of use to art buffs who've visited the Borghese Gallery 11 times and want to focus their trip exclusively on pre-Renaissance art and architecture? No. But it will save first-time visitors to Rome hours of pre-trip organizing and planning.

A few developers, it turns out, have resisted the urge to repurpose someone else's content and have instead gone to the trouble of producing something useful. Rick Steves, the writer and publisher of guidebooks and host of his eponymous PBS show, has put together his own Ancient Rome audio tour. It isn't technically an AR app, and that's on purpose: Rick Steves and his publisher didn't feel that AR added much in the way of value. The app doesn't use GPS to figure out where you are, and there's no augmented reality display. Instead, you walk up to, say, the Temple of Antoninus Pius and Faustina, press the number that corresponds with it on the map appearing on your screen, and then listen as the story begins. It helps, of course, that Rick Steves has unearthed plenty of fascinating information. But best of all is the fact that instead of squinting at a 2.5-inch-wide screen, your eyes get to take in the glory that is the Temple of Antoninus Pius and Faustina.

The Condé Nast Traveller Insider Guide to Rome (created by the British edition of this publication, which is editorially independent from it) proved to be, along with Google Maps, the most useful app on my iPhone. The reason? Good taste. It may feature a fraction of the number of restaurants in the mTrips guide, but the three I dined in were all good and onea hole-in-the-wall in the Jewish Ghetto called Sora Margheritaserved the best lamb shoulder I've had in years. Stuffed and euphoric, I wandered out to a public square, sat next to a fountain, and used the app to look for nearby shops. It suggested a leather goods store called Ibiz, which designs and makes its own bags and purses, and the map showed me the way. I arrived in minutes and, once inside, e-mailed photos of several samples to my wife, and, seconds later, was informed which purse I was not to return home without.

That, people, is a travel app easily worth more than its $6 price tag. Too bad it crashed permanently on the third day, before I had a chance to try one of the audio walks.

Such is the pace of change in the app world that by the time you read this, some of the information will already be obsolete. That is a good thing, because the future promises to right the many wrongs of the present. According to the product manager for Google Goggles, Shailesh Nalawadi, as more people scan through its suggested Web links and click on the one they want, Goggles will learn to make better suggestions (bad news, perhaps, for ARCO gas). In the future, it may even be possible for users to filter results according to their needs. "One possibility," Nalawadi says, "would be taking a picture of the Colosseum and simultaneously speaking the word history into the phone mic to get specific historical content." In the meantime, Google is downloading more photos of landmarks, expanding its collection of wine labels, and, as always, working on new and better algorithms.

The day may come when augmented reality refers to something other than a jiggling smartphone screen cluttered with useless data. In smartphone app circles, there is talk of AR goggles. Travelers may one day be able to walk down streets in foreign lands and have useful information projected directly onto their retinas. Others say the future isn't about the eyes so much as the ears. Brooke Burdick, who is the director for business development at Rick Steves, believes audio is the killer mobile app. "Travelers don't want to watch a video of what they're going to see," he said. "Visual gizmos can be a distraction."

Then again, is technology really the issue? The smartphone of today may not take audio commands or do retinal projection, but it's not exactly underpowered. The best apps I tested were those that used original research. No self-respecting guidebook, after all, would dare to publish Wikipedia entries or random tweets. Why should mobile apps be any different?

My favorite guidebook of all time is The Food and Wine Lover's Companion to Tuscany, by Carla Capalbo, and I love it for the quality of its information, the richness of its details. My wife and I took it on our honeymoon eight years ago, turning what could have been a two-week odyssey of tourist-trap disasters into a dreamlike series of gustatory revelations. Our greatest memory is of roast pork loin covered in apple slices and white truffle at Osteria del Contadino, in the otherwise minor town of Guasticce. Our second-greatest memory is of the shouting match we got into on the way there, after getting lost near Livorno. Google Maps just wasn't an option. So Ms. Capalbo, if you're out there, a word of advice: Your next book should be an app. I for one can't wait to read it.