If you were a fan of the first two, you'll definitely enjoy this one.
Although it has little in common with the source material (the games), the story manages to be just as interesting. The rundown is that it picks up a few years (8, I think) after the second one ended.
(This bit might be a bit of a spoiler for those who haven't seen the second one)
The T-Virus has infected the world. Not just people, but animals and plant life have been decimated by it, and the world has been turned into a barren wasteland. A few survivors travel from small town to small town searching for supplies. They avoid bigger cities out of fear of the zombies.
(End possible spoiler)
My ratings are a bit skewed because as long as the movie entertains me for the full duration of it, I'll score it very highly. And seeing how this movie did that, I'm going to give it 10/10.
I found it good too. 10/10 from me.
On a side note, I barely remember the other ones. So everything in this one seemed new to me.
Veronica much?
Can I get some spoilers, please? :)