Good attempt... Could have been a lot better!

Rating: 7/10 (8 August 2009)

I'll start with the good stuff: the movie captures the game's atmosphere pretty well, the visuals, the panic, the creepiness... it takes all of the good elements of the game and blends them together in a pseudo-original storyline.
It somewhat captures the feel of the game but sadly ultimately fails to deliver!
(Slight spoilers below)
First of all, monsters in SH games are not random apparitions... they aren't there for no reason, and their look and feel is usually custom-set for each game. The monsters are part of the experience as much as the story, as much as the scenery. Each individual one of them plays into the storyline and has symbolism attached to it (for example in SH 2, towards the end of the game you encounter some frame-bed-with people on top -monsters -> these blend into the story with one of the characters who was victim of rape - and the monster looks like an ongoing rape-scene - and with the main character's own story about his wife who's death-bed image he's haunted by) -> in the movie monsters are just there, there is no particular reason for them to be there or for them to look the way they do. They are all easily recognizable from the games but they don't make any sense with the movie's storyline.
Second, SH stories have always a double meaning... one in which you accept the premise of the SH monster-town and one in which SH is just another symbol for unconscious nightmares. All first 4 games have worked this double meaning masterfully (the 5th, which is very much based on the movie fails in this regard also). The movie just gives one explanation, the monster-town explanation and doesn't give room for anything but the supernatural explanation (the ending leaves nothing to imagination, telling viewers that the two main characters are forever trapped in the Silent Hill parallel universe).
And third, another crucial element in the games, is the storyline, how the character's experience slowly gives the player clues about what's actually going on, helping the player along in solving the mystery. The games do have one or more "revealing scenes" but nothing as poorly executed as the movie. In the movie there is practically almost no progression, by the time the stage is set and the story gets in motion, time's up and you get the explanation all blurted out at once in sort of a flash-back old-style reel. There is virtually no build-up to it, no progression in story, in discovery, in mystery.
And fourth, as another commenter already pointed out, SH is downright scary and disturbing. Playing the game alone at night is sure to send icy shivers down your spine, make you feel trapped, alone, isolated, confused, curious, sick, insane etc. Out of all of that palette of feelings the movie only manages to bring across "eerie" and that's about it. In the final "descent scenes" I had the feeling of watching the Doom game-to movie conversion in which game-fans are treated to the first person shooter perspective (in SH the familiar map-navigation and stumbling through the dark). But in the game that is a whole experience, something you live through... the movie only REMINDS you of that wonderful feeling, instead of GIVING you the feeling.
People who played the games will find themselves in familiar territory and will enjoy the movie more or less. People who are not familiar with the games sadly won't "get it"... They won't "get" what Silent Hill is all about, they will only get a slight "feeling" about it... but it barely scratches the surface!
All in all it's one of the better game to movie transitions, but as most it fails in many regards to convey the elements that made the games they are based on great and make them come to life on screen. At least it tried, and it stayed true to the original in most regards.