The movie is funny in parts, but I'm not sure where all of this critical acclaim is coming from. It is very raunchy, so I advise not watching it with your parents (or anyone else you would get embarrassed around) if at all possible. I actually thought the movie was about half an hour too long (it ran about 2 hours and twenty minutes).
To me, the bright spots of the movie were supporting case Leslie Mann (she played Heigl's sister) and Paul Rudd (he played Heigl's brother-in-law). I thought both added a lot to the film. If someone asked me if they should spend the money to go see this film, I would probably only suggest it at matinee pricing. $10 on this movie would be a stretch, but that is just my opinion. I would give Knocked Up 3 1/2 out of 5 stars.