It's not really a horror game and it has some problems with tone, going from weirdly humorous to creepy in a jiffy, but the antagonist's phone calls are really, really leeching the creep out of the atmosphere, adding some levity.
The game itself is an interesting mix of first person exploring, puzzling, shooting and jumping, though the levels are a bit long and inconsistent in my opinion.
Setting and story held my interest right up until the end, propping up the rather average gameplay loop to make it a decent overall experience.