Well, this is another soul-sucking book that caused me to lose entirely too much sleep because I'd find myself thinking "just one more chapter." I'm usually pretty good about putting a book down when I'm tired...but this was a hard one.
The comparisons to Hunger Games are pretty obvious in here, but luckily there's enough differences between this world and Hunger Games that it wasn't noticeable after getting through the premise (small girl that's tougher than she looks competing against stronger people, and quite brutal at times). At first I didn't really buy into the whole idea that people could be sorted into different factions based on certain characteristics, but luckily this is something covered pretty early on in the story.
I'm liking Tris as a main character--while she's got quite a bit of strength in her, she has her doubts and concerns. The other characters are pretty interesting, as is her love interest (luckily, not too much of the time in here is spent dwelling on the romance. It's there, but not taking over the story). I was pretty surprised by the brutal events at the end, though--unfortunately some of the deaths in here weren't as effective since this was only the first in the trilogy, so it'll be interesting to see just what direction this is going in.