By far, my fave of the Apatow comedies. Like Knocked Up, his best films seem to be the ones in which he does triple duty as director, writer, & producer.
In this case, this triple-combo results in a movie whose strength lies not just with the high level of comedy (which probably would've been enough), but also for the fact that at it's heart, this is a story of a "late bloomer" that is handled not just intelligently, but even more importantly, with a genuine heart.
Ofttimes, many of the characters seem to deliver their punchlines with a tempered sense of sympathy towards the plight of the lead character, even when the results lead to a an exasperated situation of disintegrated success (a tried & true formula of the genre).
This movie can be touching & even socially in-depth at times, but without any cost the number of out-loud laughs.