I haven't read the book(s) yet, but I just saw the movie last weekend... It was ok... Sort of an action movie, but it felt like a lot of the plot was glossed over. I'm pretty sure that the screen writers were trying to keep as close to the book(s) but time constraints (in terms of the movie length) kept them from fully exploring the plot. Also being an action movie, the audience is more excited about watching the action than in learning the backstory and digging into the plot.
(Spoiler alert... sort of)
For example, the introduction to the reason for the Hunger Games was that there was a civil war (?) and the losing side (traitors) had to enter into these hunger games as retribution for being traitors (still didn't know why they were called the "Hunger Games", just that they were). Later Katniss asks Gale (her friend in their village ("district")) how many times his name is entered in the hunger games drawing and he mentions several (I had thought prior to this that each person was entered in once). Still later Katniss mentions something about not entering their name in multiple times for food, and now I'm beginning to understand the underlying story a little better. I'm guessing that there was some war or uprising over food (or lack of) and the Hunger Games are a double edged sword where people can get food credits by entering their name in multiple times into the drawing. Unfortunately most of these statements were mentioned more as an aside and if you weren't paying full attention to the movie you may have missed it.
I also felt the timing of the movie was off... In the early part of the movie when Katniss is getting tips to winning the Hunger Games, there's mention of many survival skills (finding water is your biggest friend, etc.) which suggests that the games will take place over many days, even weeks or months (sort of like today's reality show Survivor). However from the movie it felt like everything happened within a few days, maybe a week tops. Again I think it was due more to the movie wanting to hit all the action whereas the book(s) may do more expository about the plot and character interaction.
I think I would probably enjoy the movie better if I had read the book first, but I also don't think that the movie was a complete waste of time or money. I'd be interested to here from people that have read the book and how they felt about the movie...