I'm not really a fan of stars taking on new accents unless it's done really well, I think you could still hear the Scottish in Ewan's voice, apart from that, I enjoyed his performance.
The story seems to inflate to an unweildly size, but this is often a symptom of a movie taken from a book. Thankfully, this sense of sprawl manages to give a sense of depth, and not a sense of unexamined and cursory detail.
A dose of originality in a genre which usually accepts tried-and-true formulae.
I actually had fun watching this movie. It didn't have the strongest story, and the acting is hit and miss, but the way it unfolds, the shot selection, and the overly plucked strings of anticipated and impending doom, worked well for me.
Bottom-line, I was entertained. If you're into psychological/horror-thrillers, give this one a shot.