I've read the whole trilogy. As you said, I liked the first book, but they did decrease in quality from there. I also found the characters cliched and predictable in many ways. There was a bit of controversy over the similarities in concept and plot between The Hunger Games and Battle Royale, which is a Japanese novel published a few years before. It has the same setup, and while it's more violent than The Hunger Games (the Japanese government considered banning it), it is very very similar. It's possible that it's a coincidence, but the sheer scale of the similarity is a bit difficult for me to ignore.