Well I thought 40 year old virgin was decent, some real funny parts, but nothing outstanding. I thought Knocked Up was pretty good, a definite improvement over Virgin, but still, neither are anything I'd watch very much. I was really looking forward to Superbad, and while it has some good stuff, mainly the cop/McLovin parts, it was pretty disappointing. It was way too long I think at nearly 2 hours. Most of the laughs weren't that great, and because of the length they were often times too spread out.
Hot Rod was MUCH funnier.