Enter The Void

The addition of vertical cover was a much ballyhooed innovation to the game.  Although it isn't quite as amazing a feature as the developers would have liked us to believe, it is still an interesting mode of cover and makes for some fun moments in the game.  Basically, whenever Will encounters a cliff face (or an assembled facsimile of a cliff space, like a reactor core or the side of a building), he can duck down into a crouch and peer down the edge and see enemies below climbing their way up to him.  You can target, shoot and throw grenades just like you would when you are in normal cover, except that when you're ready to advance ahead you tap a button and Will jumps/falls to the next platform.  Once you have the rocket pack the same works in reverse and Will will climb from platform to platform with a short burst from his jet pack.  Visually, it's a seriously cool effect; firing up into the air and seeing your fallen enemies whizz by you on their way to oblivion.

Speaking of the jet pack, the flying in the game is a lot of fun.  There's really nothing cooler than taking to the skies in your own jet pack.  Will's rockets never run out of fuel, or ammo and you can barrel roll and loop de loop to your hearts content.  You can even cut your engines whenever you feel like it and go into a skydiving free fall, then just before you hit the ground light them up again and zoom off into the sky.
The developers knew flying would be the main appeal so they made sure that in most of the levels, Will always has the option to take to the skies, blast airborne enemies, strafe ground-based enemies, hover and out flank cover-based enemies then land and punch enemies in the face.  Most of the levels allow you to attack as you see fit, allowing you to go from full flight to ground-based cover whenever you want.
The graphics in Dark Void are inconsistent.  At times, they are utterly breath-taking for instance when Will jumps onto an enemy UFO, the rockets on his back glowing red as they cool down, hurtling through a stone canyon as the sun sets in the background.
The biggest problem with the games visuals is also one of the bigger pluses to the game's visuals and that is the size of the levels.  Most of the levels in Dark Void are absolutely huge, but it also means that when you get up close to anything it lacks detail.  The interior levels all seem to have a spartan, clean look to them.  Even in ancient tombs that are supposed to look like they've been abandoned for centuries, there is not much inside them except for the geometry of the room.  No cobwebs, not much texture, just walls and floors.
The character models are also inconsistent.  Some characters look fantastic, while others are a bit off.  I would chalk this one up to design choice.  Similar to, but not as pronounced as, the Tomb Raider series the characters all look realistic, but have slightly exaggerated, almost cartoon-like features.  This is especially notable in Will's face.  His eyes are a little too large and his jaw, a tad too pronounced.  It's not really a short-coming, but the props, such as the weapons, jet-packs, machinery and even some of the enemies are all rendered in hyper realistic detail.  So it is slightly strange when Will takes off his ultra-realistic robotic helmet to reveal a slightly cartoonish face.
The productions design behind the game is nothing short of inspired.  Especially in regards to the Watchers and their technology.  Whether it be the props or the vehicles everything looks well designed; a great deal of thought was put into creating the details of this new fictional universe.
Where the game really falters is the cutscenes that bridge the gameplay.  The cutscenes are all interesting and do a good job of advancing story and character development, but many of them are edited and paced in a jarring way, detracting from the very thing they are trying to convey which is an immersive storyline and rich characters.  The cutscenes seem to trip over themselves and the frustrating part is that you can generally see what they were trying to accomplish or what is is that they were going for, despite the poor execution.
Sound in Dark Void is also a mixed bag.  On the one hand, one of the best aspects of the game is the soundtrack.  Composed by Bear McCreary as an homage to some of his favorite adventure movies, the soundtrack is fantastic and mixed into the gameplay in a dynamic way.  
The sound effects are all decent, however if you have a favorite weapon in the game, the sound of it firing will likely becoming irritating after a while.  I also experienced a glitch at one point where the sound for Will's actions cut out completely.  The jet pack, his weapon, and footsteps were all silent but his voice was still sharply audible.  
Speaking of voices, the voice cast for the game is top-notch and the veteran actors seem to have done the best they could with what was written on the page.  The hero is voiced by the ever-present Nolan North, who is a decent fit for the character.  Other notable cast members include Paul Eiding (aka Col. Roy Campbell from the Metal Gear Solid series) and Polly Walker as Ava. 
Dark Void isn't particularly challenging, although there are multiple difficulty modes and the option to change difficulty on the fly.  The game's story mode will generally last between 6 and 8 hours.  The missions are all repayable thanks to level select and a bonus mode containing "Survivor Missions" is also available as DLC for $4.99.
In the end, Dark Void is a game that had a lot of potential and the developers were able to deliver on much of it.  Hurtling through the air blasting robots in the future/past.  The things that Dark Void does right great outshine the things that Dark Void does wrong and it is definitely worth playing.