Big thumbs up here. I saw this yesterday afternoon. John Zmirak over at Godspy has written a review that says most of what I wanted to say already. (Note: his review does contain spoilers, but nothing that will take away from the impact of the movie).

One recommendation: unless you have committed yourself to a point-of-view that regards spiritual warfare as patently silly and medieval, go see this film as a matinee rather than late in the evening.

For more information about exorcisms, check out this article over at Catholic Answers.