TMS is my favorite show. Is, was, and always will be.
That said, I wanted to like MT but didn't. IMO it represented beginning of the shift in tone that characterizes many of the Muppet productions today. I agree with Heralde's "teenagers acting like adults" comment. The humor was less subtle, less layered, less intelligent (absent the Jerry Juhl touch). The musical numbers were short to the point of non-existence. The new characters were pretty broad, not nearly as complex as their forerunners. The guest star 'flashback' sketches got old quick, as did most of the regular features (which were foundationless), as did Andy & Randy Pig and to some extent Big Mean Carl.
As far as the 'adult' humor, when did 'adult' become synonymous with innuendo? Is it not possible to appeal to adults (or perhaps the term 'grown-ups' would be more appropriate) without being inappropriate? What was adult about the humor on TMS was the intelligence and wit, not cheeky innuendo. Just like guest stars vs. guest hosts, the general populus doesn't know the difference anymore. Think of what they did to Scooby-Doo and the upcoming Alvin & the Chipmunks on film- modern, 'grown-up' (but really the opposite) revisitation that has nothing to do with the source material.
The show had its moments (I can point to several that stand out) but never fired on all cylinders. Sketches and the characters therein had a tendency to be pretty random, and the show never felt cohesive. The show's move it along pace might've worked if they hadn't tried to incorporate the backstage elements. The attempt to mix old and new characters only served to marginalize both sets, never allowing for the depth of character that distinguishes the classic Muppet productions.
I may post more thoughts later. It's been a long week.
David "Gorgon Heap" Ebersole