Why you shouldn't watch this
1) If you're expecting Jack Brooks to be slaying a variety of monsters throughout the flick (as the title would make you assume), then you shouldn't watch this.
2) If you're expecting Jack Brooks to be like Ash from Evil Dead (with the witty banter DURING action scenes), then you shouldn't watch this.
3) If you're expecting a satisfying and complete movie experience (rather than an introduction to a series), then you shouldn't watch this.
Basically the movie is the first part of a series (as the sequel has already been announced). The title, for this part, is misleading, Jack Brooks isn't the badass you'd expect since too much time is wasted with his little problems, and after the movie is over you're left thinking "this could've been accomplished in 30 minutes...not 1 hr 30."
BUT! Reason why you SHOULD watch this:
1) (To my knowledge) ALL creatures and special fx are NOT CGI (and they look great!) Any makeup artist/creature creator would LOVE to see what they accomplished in this flick and I'm incredibly glad to see a new director avoiding CGI. CGI just isn't scary.
2) Acting is actually decent (except I hated Jack's girlfriend's screamy voice).
3) You'll be comfortable jumping into part 2!!!
Overall, my score: 5/10. It's not bad, but then again it could've been so much better. Don't listen to those who have over reacted and claimed the movie sucks... it just could've been better and if your expectations are right, then you'll appreciate it.