Let me start by saying I'm a Seth Rogen fan. I think if you liked Superbad, Knocked Up, and Pineapple Express, you'll love it. If not, I don't know what to tell you. Its basically the same main cast from Pineapple Express with several cameos. Michael Cera will probably shock you (he was hilarious)
It's kind of one of those 'stupid funny' movies with somewhat of an underlying religious (but not THAT religious) theme that plays a factor in the end of the movie. Don't let it scare you away, because it's definitely not preachy or anything. Personally I laughed until I cried. I thought it was really really funny.