Saw it on Wednesday and thought it was an incredibly charming movie! The tone is just right, every time you think you're ready to roll your eyes at some cutesy joke, they completely undercut it in a way that still manages to be funny and sweet at once without ever becoming cynical or taking itself too seriously. It reminded me of the humor in ENCHANTED which I thought worked so great. It's just the kind of movie where I couldn't stop smiling from beginning to end.
The new Muppet, Walter, was sort of the least interesting character just because he plays a sort of everyman type, but Jason Segel, Amy Adams, Chris Cooper and a whole bunch of actors who do cameos (I particularly loved Emily Blunt and Alan Arkin) were all terrific, completely getting the tone the movie was going for without looking awkward. However, what I think the movie succeeds at the most is at making the Muppets the real stars of the show, it's such a nice love letter to them and Henson's legacy. Miss Piggy is still my favorite and her lines here are priceless, but I thought all the scenes involving the Muppets interacting without human characters worked perfectly.
The musical numbers are all great and done in a really smart way, the finale is terrific. And at the risk of sounding like a cliche I have to say it was so refreshing to see a family movie that is done so well that it doesn't need to rely on 3D, computer animation, or big special effects to make up for bad script, characters, etc.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"