Nothing much has changed in my opinion between reading Uglies, and this sequel, Pretties. It's okay young adult dystopian fiction, but nothing special. That is to say, it's readable, it's even relatively enjoyable, but it's not deep. The world is fairly black and white, and even Westerfeld's attempts to complicate the picture read as mere sketches, rather than actual dilemmas.
I just don't believe he'll ever break his toys. Maybe the third book will prove me wrong, but I'm in no hurry to read it. I just don't believe that bad things will ever happen to characters we care about (rather than peripheral red-shirts), and so there is no sense of intensity. People will be captured, but that's about it.
It's probably unfair to keep comparing these books to The Hunger Games, but stakes are high in The Hunger Games, in a way that they are not in Uglies/Pretties. In these books, all the characters are always wearing crash bracelets, metaphorically. There is no real edge of danger, not even to the death-defying jump in this book, as it's made quite clear before Tally takes it, that it will be quite safe, in the end.
Drama comes from the potential for actual disaster. Clear avoidance of consequences lessens drama. This is why I love Joss Whedon, while simultaneously calling him a bastard. The man breaks his toys when he needs to. Things happen. Repercussions happen, and have lasting effects. This is a model Scott Westerfeld could learn some things from.