The first one was great, and okay, they got a trilogy out o'it. Well played. But as it was they were running outta new gags by the end of 3. 4 was going too far and it pretty much lacked any real conviction.
I would rather watch Johnny Depp make omelettes for 40 people than whatever the f*** 5 is gonna have in store.
I hear Tina Fey might be in the Muppets, though.