I want to say up front, that I have not played the video game so my review deals with the film on it's own.
The sets and monsters were superb. They created a very creepy, and at times disturbing, atmosphere. When I sat down to watch the DVD I wanted to see something visually immersive and I was not disappointed. The burning creatures, 'Pyramid man' and the external shots of the town were especially good.
The story was entertaining and challenged me to work out what was going on throughout the film. Although it was quite linear the plot progressed well, revealing new twists right up to the end. Three days after watching it I am still thinking about the ending... Some set pieces seem to have been dropped in just because they looked good, rather that because they kept the story moving forward ('armless monster', the 'nurses' and the 'blade in the boiler room' for example, and why barbed-wire in the finale?) but as this sequential style with lots of set pieces is the format used to create video games I was OK with it for this movie.
The acting was competent if not engrossing. I would like to have cared about the characters a little more than I did, even more so as most of them were female. The two extremes of the competency scale for me were Deborah Kara Unger who seemed to be playing an airyfairy pantomime witch, and Jodelle Ferland, who was superb.
I bought this DVD because it was cheap, the cover-art looked good and Sean Bean was mentioned in the cast list. I'm glad I took a punt. In hindsight I wish I had spent even more and seen it at the cinema: it's worth it.