I enjoyed The Hunger Games, so this second installment was a bit of a let-down. Katniss went from being a slightly one dimensional (common enough in YA books that I let it slide), but strong and fairly likable heroine, to being a complete idiot for most of this book. Whereas in book 1 she saved Peeta and other characters numerous times, in this one she turns into a damsel-in-distress who needs to be led through the arena by Finnick and comes up with asinine plans. Collins tries to throw in a bunch of **cahraaaazzzy** plot twists that are actually very predictable, and the fact that Katniss acts shocked at each of these only serves to make her seem more ignorant. How does it take her nearly the entire book to realize the mockingjay is the symbol of the rebellion, when we've been hit over the head with it from the first page? Some of these twists were actually surprising, and a few were even decent plot points - for instance, the layout of the arena. But for the most part it seemed like Collins was just writing a (worse) version of book 1, and trying to cover for it by throwing in nonsense.
I found the whole love triangle thing completely grating. I agree with another reviewer who said Peeta and Gale are basically the same character, and neither is very interesting. Also, since Katniss is so annoying in this book I was even more annoyed with both of the boys for liking her since I couldn't figure out how they possibly could. She flip-flops so much in this book: "I love Gale! No, I love Peeta! I want to run away! No, I should stay here and join the rebellion! I must survive another Hunger Games! No, I must die and let Peeta live! I should kill all of my allies! No, I think I need them!" Make up your damn mind already. It's another of Katniss' overwhelmingly irritating personality flaws - and flaws are most of the personality she has in this book.
All in all, this book feels like a stepping stone. It seems Collins knew she wanted to write a trilogy and just didn't know what to put in the second book, so she wrote filler. The pacing is really bizarre and seems rushed in places, like she just wants to get her paycheck and get onto the next book. The cliffhanger at the end is totally unnecessary - and I say that as someone who's not really sitting in suspense and rushing out to buy the next book immediately. It really just seems designed to sell twice as many books - otherwise why not edit some of the crap out of this one and combine it with the next?
I'm sure I will end up reading Mockingjay, because I want to see how it all ends, but I'm not gonna get my hopes up.