Tough Call - I grew up on this movie and had no idea of it's backstory other than that "Dad from Beethoven" was on it when we got it on VHS. I watch it nowadays and either cringe at the music sequences or laugh my ass off depending on the scene. You can't beat the fact that Charles Grodin was in a Muppet film as a supporting actor with a crush on Miss Piggy. And the cameo appearances of John Clease and Jack Warden really held up well.
Overall, I like it a lot but its not on the same level as "The Muppet Movie." It's hard to hate on anything Jim Henson directing live-action movies - he was a beyond genius.