I really liked The Hunger Games, but I missed a more extended explanation of Panem and its society. And Catching Fire gives us that. In the first part, at least.
The second book of this trilogy starts off in District 12 some time after Katniss and Peeta have survived the 74th Hunger Games against all odds. Now they have to tour the other 11 districts and the Capitol as victors, which is an extra challenge for Katniss, as her idea to use nightlock to commit suicide was the sparkle that could start the fire of rebellion in the districts. So President Snow basically tells her she needs to stop any ideas of rebellion from catching if she doesn't want a lot of people to die. Plus, it's Quarter Quell, a special edition of the Hunger Games that takes place every 25 years, and in this particular games, the victors of past games become tributes. Will Katniss and Peeta survive their second visit to the arena?
The book is divided in two big parts: the first part shows us what happens after Katniss and Peeta make it safely out of the arena. It was interesting to see the rest of Panem, all the other districts, the Capitol itself, the people, the reactions to the victors... And the political tension between President Snow and Katniss. The second part takes us back to the arena, and you cannot really skip that but I'd say it's the most "boring" part in the sense that it feels like a repetition of the events in the first book. However, it's important because it leads to the events in Mockingjay, so there you have it.
Catching Fire is all about politics and Katniss realizing her own feelings not just towards Peeta and Gale, but towards the world around her. Involuntarily, Katniss becomes a symbol for rebellion and for hope. The whole tension in the interactions between Snow and Katniss added up to all the violence that she and Peeta encounter while travelling around Panem make the first part of this book the best part of the whole trilogy, in my opinion. They are forced to open their eyes and choose between playing along or fighting against it. As a side note, I also liked to see the contrast between the poor Districts and the opulence in the Capitol.
A not so positive aspect was the repetition of the Hunger Games. It was interesting in the sense that we get to know new, very likable characters that will later be of great importance, but the hours spent in the arena were a bit boring and redundant for my taste. Maybe that's the reason why a lot of people think this is the weakest of all three books?
All in all, Catching Fire is, in my opinion, the reason why everybody needs to read The Hunger Games trilogy. It must be read together with Mockingjay (don't wait for a whole year to read the last part, like I did) in order to get a more complete picture.
Here is the official trailer for the Catching Fire movie, which premieres on November 22nd, 2013.