It's okay. Not executed perfectly, but still pretty entertaining.
Russel Crowe is great in it.
I guess my thing with exorcism movies is that maybe it's more compelling if you actually believe any of this shit is real? I find some of the horror to actually be funny, and I find myself (especially in the case of this film) cheering for the demons to take over the awful Catholic priests. I have trouble seeing them as protagonists, heh. This movie sort of goes part Evil Dead. I would have liked it more if it went FULL Evil Dead! It gets some credit for using set design and mood and set pieces and such instead of just jump scares or something, I guess. But I still didn't really like the protagonists enough to cheer for them. *shrug* (It would take a lot for me to sympathize with Catholic priests.)
[SPOILER - highlight to read]: The bloody naked girl bubbling up and exploding was pretty awesome, though. That rocked.
7/10 from me.
I guess I'll let Rob keep his d!ck. But just barely!