Firstly, I must say that I really thought the first book wonderful and exciting, and I had high hopes for the 2nd. Secondly, I read all three, and I would like to point out a few things that are left out in comments like "I loved this, a must-read!"
The first book, as I said, was great. It was well-paced (didn't feel rushed), surprising (waiting to see what will be next), and emotional (who of the two District 12s will die?).
The second book, however, started off by picking up the loose ends from the 1st book, which is reasonable. Except, I felt like a lot of new detail was synthesized on the spot, and rather clumsily (forgive me, but that's how I felt). A major event (not to spoil I won't write it down) that starts the action-ball rolling feels unnatural and unexpected in a sense of "well, here we go again".
For what I liked, it's the "good stuff" and drama from the 1st book, which lives up to the 1st book; it felt repetitive, however, and didn't seem have much to offer (again, this is my point of view, you might disagree). I felt hanging in mid-air, rushing through the pages not because of excitement (as it felt rather obvious that there is going to be a way out), but just to see how the problem will be solved.
Also, the lack of development of the new characters in the book, and how no-one vital to the "plot" was accidentally killed (which, in my opinion, would have made the story so, so much better!) was unfortunate.