I feel that by season 3, The Fast Show had really got going and had become really funny. Paul Whitehouse is an absolute comedic genius, and his characters are always my favourites. My fav sketches are the ones with the old guy who mumbles away and then ends it with "I was very, very drunk" and the "scorchio" TV station.
The Fast Show is quite repetitive, tending to use the same sketch idea over and over again with new ideas in it. However, it is still very funny, and also this kind of format tends to produce memorable catch phrases. I still find myself saying "Suits you sir!" way more often than is necessary!