Muppet Christmas Carol is my favourite movie of all time and I absolutely love the Muppets (and the Haunted Mansion is one of my favourite Disneyland rides) so I was both excited and nervous to watch this special.
I really enjoyed the first half -- the songs are fun and quite catchy, there are some pretty good moments and jokes (the goat's appearances made me laugh out loud) but the second half was really strange and creepy -- and not in a fun way. It definitely doesn't deliver the same level of pure joy as Muppet Christmas Carol but, to be fair, that is a high bar to meet.
Also, not enough Rizzo.
(I also miss Steve Whitmire's performances but sounds like they're better off without him, here's a paragraph from Wikipedia on his dismissal: "Brian Henson stated that issues with Whitmire began in the mid-1990s, and said that Whitmire would make "outrageous demands and often played brinkmanship", and additionally stated that Whitmire would "send emails and letters attacking everyone, attacking the writing and attacking the director". He also expressed guilt for not dismissing Whitmire and recasting Kermit before selling the Muppets to Disney in 2004, because "I knew that it was going to be a real problem". Lisa Henson stated that Whitmire was opposed to having an understudy for Kermit and refused to train one, which became problematic when it came to "B-level performances, such as a ribbon-cutting," at some of which she said he was unwilling to appear. She also stated that he "blackballed young performers" by refusing to appear in shows with them.")
