The movie was pretty good up until Henry was imprisoned at Gosselin's Market. After that, they proceeded to cram approximately the entire second half of the book into 30 minutes. Plus, I don't remember Duddits being a fucking alien at the end of the book.

The other thing that bothered the hell out of me was that they never even bothered to explain what happened to the people infected with the Byrum. In the book, it's explained that the Byrum can't survive in the harsh winter climate, and as such would need to be rapidly transported into a mass number of hosts and therefore transported to warmer climates so it could survive and spread more. That's why Mr. Gray was trying to dump that dog into the reservoir. They didn't even bother to explain that, or explain the fact that all of the people at Gosselin's eventually got better and were set free.

The first chunk of the movie was pretty good, but everything after Henry's imprisonment was complete crap.