This is a brilliant comedy. The problem is that the comedy is subtle, or relies on you paying attention to previous seemingly mundane scenes.
I can definitely see how some people would find this film boring. It's not the typical slapstick comedy that comes out every 4 months. The comedy in this flim relies mostly on portraying the ridiculous character of Steve Zissou and his equally oddball crew. You'll see Bill Murray delivering brilliantly witty lines, as well as a couple of memorable sight gags. You can't really rate the acting in this movie, since all the characters are over the top.
Typical comedy of this film...scenes are occasionally interluded with a guitar player strumming out tunes. It might take a few songs before you realize he's playing David Bowie songs in Portugese.