I have read all three books and saw the movie earlier this week. First of all in a vacuum the movie and first book are good, a 7/10 is about what I would give both. The problem with The Hunger Games is that neither the book nor the movie exist in a vacuum. They exist in the real world and a more superior version of both already exists.
Battle Royale while not well known in the US (it did not get wide release here because of the Columbine tragedy, a fate that would have surely been shared by The Hunger Games if it had been released a decade ago)was/is an international phenomenon and with good reason. The book is stunning and does not flinch away from ANYTHING. The movie even more so. It is the hard R version of The Hunger Games. There is no shakey cam to hide the violence, it almost revels in it. The other difference between the two works in the back story of the characters involved. In THG they enter the arena as relative strangers, the only issues they must grapple with are the difficulty with taking a human life. In BR the kids are all from the same class and small town. They all know each other. They all have history with one another, and are handed weapons and asked to start killing their classmates whether they be friends, rivals, or even lovers. The difficulty and ease that different characters have with adjusting to that development is something that is handled very well in both the book and movie and that in my opinion THG was lacking.
As far as the film itself goes I felt that it faced a difficult problem. It was too long (at about the two hour point my wife and I were both getting fidgety) but it also was not thorough enough.
Some of the greatest book to movie adaptations of all time took the original story and made it their own. They had a general plot or conflict that they sought to get across on the screen but by no means felt shackled to going chapter by chapter through the source material. This process can produce The Shining, Apocalypse Now, and Blade Runner, but it can also backfire and give us I Robot or I Am Legend (die in a fire Will Smith). It is a risk but it is a risk that a director almost certainly must make in order to create an enjoyable and coherent film from a book.
THG chose to go the safe route. The director most definitely was flipping chapter to chapter and putting no more thought into it than "how to I make that happen on the screen". Luckily the film was not as big a mess as some others that took this route (looking at you Golden Compass) but it still was fairly sloppy.
The only scene in the film that was given time to work was the Reaping near the beginning of the film. The rest of the movie seemed like it was in a hurry to fit a scene from each chapter into a running time that audiences would at least tolerate. They succeeded in that (barely) but the end result is not nearly what it could have been. Instead what we get is a Cliff's Notes version of THG on the big screen. Future generations of freshman English students who would rather watch the movie than read the book will rejoice.
So to recap
The Hunger Games book, 7/10
The Hunger Games Movie 6/10 (dropped a point because it is BR for kids)
Battle Royale book 8/10
Battle Royale movie 7/10
It should be interesting to see how they handle the sequels to The Hunger Games
The Hunger Games II: You Mean They Will Pay Me To Write The Same Book Twice
and
The Hunger Games III: The Search For More Money
The second one will be a shot for shot remake of the first and the third will be utterly unfilmable. Buckle up folks, this one was decent but it is all downhill from here.