I like my comedies on the darker side, so this one was right up my alley. It's not on the "Bad Santa" level but it's still entertaining.
Warning for those expecting a big moral lesson: You won't find it here. The Cameron Diaz character proves you can get what you want by lying, cheating, and stealing. Several on-line reviews I read have a problem with that. I didn't. It's a movie, and a dark comedy at that.
While you really can't root for the Diaz character, you can root against one of her enemies-- a way too perky, way too nosy, and way too annoying fellow teacher. I hate that type.
I can't say I loved "Bad Teacher," but it was better than okay.
