The storyline has been taken from many other movies, all where the main character is also the killer (sorry if that spoils the ending...but let's face it, you would have seen it coming anyway). The acting is sketchy at times, but the characters are decent enough.
I felt that honestly, too much was going on. If the 'monster' was taken away, i think the movie would have worked better.
Regardless, it was an ok Sunday afternoon movie.