I Don't Get It

So I finally saw Knocked Up over the weekend and I thought it was ok. Not great, not bad. Just ok. It had some funny lines, like most of the sister's comments and there were even a few references that I really got a kick out of like the mushroom trip to Vegas. But overall, I didn't think it was very funny and it lacked energy. Considering that most of the people I know who saw this movie said it was "great!" and "the funniest movie", what did I miss?