This review will contain spoilers!
In many sentences:
I am so glad that Catching Fire did not devolve into a mere romance novel after the ending of The Hunger Games. The love triangle is still there, of course, but it serves to add color and depth to characters as they attempt to free themselves from the rule of an evil government. In fact, the lack of focus on the love triangle actually makes it more meaningful and more interesting in the long run. There is so much else happening that you don't get bored or annoyed with characters acting in foolish, unbelievable ways (unlike, say, the Twilight series where without foolishness we wouldn't have more than a good short story).
Other than to say that, there isn't much I can add to my critique of the first book. Catching Fire is just as good, just as exciting, and just as highly recommended. The series is going places and the second book proves that. I would, however, like to mention a few of my favorite parts. First, the twist of the Quarter Quell is excellent. I was not expecting Katniss and Peeta to have to enter the arena again, and was looking forward to the different perspective of them being mentors to new candidates. While I was disappointed this didn't happen, I enjoyed the second Hunger Games for Katniss enough that I won't complain.
I also really enjoyed the end, when Katniss is forced to stumble, delirious and injured back to the lightning tree in attempt to find Peeta. Collins did a great job here if conveying delirium, confusion, and Katniss's struggle to solve the mystery, without resorting to obtuse language or unclear actions. It wasn't confusing to the reader what was happening, but you could feel Katniss's struggle. In other words, just very well executed.
I think the biggest problem with Catching Fire is at this point, you don't have any doubt that Katniss is going to make it out okay. Most of the time you aren't spent wondering if they are going to break the rules and escape, but rather how they are going to. This isn't enough of an issue to keep someone from reading the book, but it definitely tones down the excitement and thrill that I experienced in the first book.
As with most sequels, the biggest compliment I can give is that this book has me very excited to read the third. There's no question at this point if the series will become a romance story or follow the storyline of the rebellion. It's clear that we are going to be in District 13, fighting the Capital, and attempting to rescue Peeta in book 3, all of which I'm looking forward to.
Suzanne Collins the Last Line of in Catching Fire