It is a good horror movie, definately a mood piece, and I would urge anyone who likes the games, or indeed good horror (ie - not just jump+scare horror), or hell.. just really well done visuals... to go see it. My thoughts were best expressed however by Tycho from Penny Arcade:
"Silent Hill: The Movie evokes the games without accurately expressing them - to the extent that the movie succeeds at all, it is because director Christophe Gans has mastered the series' visual lexicon. It was weighed down by a faulty script, a terrible kind of smudge across the sheet, but brilliantly directed. It is in this way that it most closely mirrors electronic gaming in a general sense, though (ironically) not Silent Hill, in that it is the sterling execution of a poor narrative."
Anything more is too much, anything less doesn't quite do it justice.