I did actually go and see it last night - first movie I've seen in the theater in 2+ years! It was HILARIOUS. So many great moments where the audience was both laughing and applauding. Nick Frost, IMHO, stole all the scenes he was in. Jason's right, the dialog was really fast-paced (like, Aaron-Sorkin-esque), so if you weren't paying attention, it was easy to miss some good lines.
I agree that it's probably not going to be the classic like Shaun of the Dead, but maybe only because Shaun of the Dead holds the spot of "best humorous spin of a standard movie topic."