First hour is great.... *Spoilter perhaps*

then it takes a turn for the worse. The first hour is gripping and tense with the whole eerie Silent Hill theme going on, leaves you seriously anticipating who/what's behind all the chaos...

... Then it just falls apart. As soon as that old git turns up with the army and we find out it's some sort of weird blob looking creature revealing itself in its entirety, the film falls flat on its face.

6.5/10 or generous 7 for the first half, 2/10 for the second half. 4.5 stars is deserved.