Saw it last night. Great fun...lot's of action, eye candy, and comedy using lines from old movies. Leave the kiddies a home though. It is definitely targeted at an adult audience. (Language, sex (mostly dialogue--no nudity), etc.
School buses should be rated x. The first time my youngest kid went on a school bus, i think her was 10 he came home crying and was in shock from what was going on in the bus. After the first month there was nothing at the movies that could offend him.