We could tell from the end of the first Hunger Games book that Katniss was a rebel from the way Peeta and her were going to eat the berries because it was her idea. In the second book, we see how her actions have affected the Capitol and how they are taking it out on her. We see that President Snow pays her a visit, telling her that she is under careful observation and that they do not believe she did her berry act for true love. Under the Capitol's watchful eye, Katniss is still trying to rebel in her own small ways. She joins hands with the other victors at the interviews before the Quarter Quell and her dress even turns into a Mockingjay during the interview.
Generally, I also like the plot of the second book. I enjoyed how it focused more on Katniss and her dealing with struggles in her hometown and not focusing on the games like the first book did. The second book was more taking place in District 12 and how Katniss is adjusting back to her "normal" life after winning the games. There is the Quarter Quell but that is not even mentioned until much later in the book. In the book, we see a love triangle developing between Peeta, Katniss, and Gale which I really enjoyed. It was nice to see Katniss' internal struggle dealing with her love issues and the other problems surrounding her.
Overall, I enjoyed the second book the best because it gave us more of an inside look into Katniss' life and all the struggles she is dealing with after the games. The second book also has some very good characters and some great character development for Katniss. The ending of the book gives a very good lead into the final book Mockingjay which I thought was also very interesting.