The premise is simple: three high school guys trying to get alcohol, go to a party, and hook up with girls. It may sound typical, but the writing and acting bring it up to a higher notch than other high school comedies about sex and teenage misadventures. If you've liked any of Apatow's other productions with this gang (Seth Rogen, Jonah Hill, etc.), then you'll most likely be laughing your butt off at this one as well. I don't know who discoverd Jonah Hill, but the guy's got some serious comedic talent. He has the ability to add extra humor to every line that comes out his mouth just by the way he delivers them. And Michael Cera was just his adorable and awesome self. The guy who plays McLovin is a great comedic find as well. One aspect of unexpected hilarity was the cops played by Seth Rogen and Bill Hader. I didn't think they'd have as much screen time as they did, and they definitely added to the laughs. I know I'm going on and on about the funny, but the movie had a lot of heart as well.
ETA: Funny Interview with Michael and Jonah:
http://www.mtv.com/overdrive/?id=1564974&vid=163289 I love how they genuinely make each other laugh.