I did a quick search, and couldn't believe that nobody had started a thread about this movie at some point!
I didn't get to see it in the theater, so since it just came out on DVD recently, I finally had a chance to watch it....WOW!!
Funny enough, I saw Avatar in the theater on Tuesday, then watched this last night at home. I thought GAMER was WAY better. Good (mostly) original story idea. Excellent acting. Believable characters. LOTS of great minor cameos (Sam Witwer of TFU-fame has a great little bit part, as do James Roday and Maggie Lawson from the TV show Psych). The action was gritty and well done. The fight scenes very in your face and engaging. There's a little bit of shaky-cam work, but it's done very well, and I don't think would make anyone sick, especially if you're watching it at home.
There's a fair bit of language, gore, and partial nudity (it is rated R after all), so not for little ones obviously, but I thought it was a great game overall. Even had some really interesting social commentary to it regarding video games, technology advancement, and what people are willing to sell themselves for. I thought it was quite good, and I definitely recommend it, especially if you're a video gamer, as it's well done, and I thought it appeals well to that crowd. If you're not a video gamer, still go see it! It's not like you have to understand what an FPS is or anything like that.