Written well, to say the very least.This is simply one of the best time-travel stories I've ever read. It doesn't focus on carefully chopping the logic of time travel (although it doesn't commit any egregious errors), but on what it would feel like to trade in the century you live in.Twelve-year-old Ada wants to live in the Utopian world of tomorrow. Twelve-year-old Amber wants to live in the good old days of the past. Each girl gets her wish.Each girl discovers that things are not as straightforward as she'd like to imagine where she has gone. Each girl makes silly mistakes, adapts to her surroundings, learns to maneuver in a strange time, performs a major good deed that she is uniquely positioned to provide.Oh, and in addition to being one of the best time-travel stories I've ever read, it's also one of the best YA novels I've ever read, and I'd recommend it to anyone who is a twelve-year-old girl, and to a whole lot of people who are younger / older / dudelier.