The idea is nice, but really...it's pretty spot on, the preperations part, to the books. There would be nothing for them to add. Since the books are told in 1st person/present tense, the charactization is set up through what she sees and she doesn't see a whole lot. The movie even told more and explained more of what you don't find out til later/see in the books.There is no development of the characters, in the movie, that needed it. And it was plenty violent. Sometimes just off screen but others, particularly one scene, you see in full view of the camera.
Personally. and while I know it would be a hard sell, splitting it into two movies, one in which they preped for the games, one in which they actually took place, would have made for a much more fulfilling series. And speaking with a few others who have seen the movie and read the books, many of them mirror my thoughts.
For me, I think it's one of the greatest book to movie adaptations I've seen in quite a while. Sure there were things left out, but nothing I deemed damning to the movie. Honestly, I would highly recommend it. I thought it was well casted, well acted, beautiful music, accurate- but still explained enough that someone who hasn't read the books would still enjoy it. The hand-cam was a little shakey for me at times, though.