Well, I just finished reading it. I liked the summer and winter issues the best. I feel like it turned out to be a good thing that winter was moved to the end as opposed to the beginning, as it's a better finale to the series than fall.
I wish this would have included more obscure characters who hadn't appeared in previous issues. I think Luncheon Counter Monster is the only such character to appear. I don't know how much of the storyarc was completed when Roger Langridge decided to leave the series, but it would have been great if he'd have tried to include more characters who hadn't appeared in previous issues, like Doglion, Lips, Timmy, Marvin Suggs, Gaffer, Fleet Scribbler, and so many others. I know he once said that he didn't know what to do with Lips but would include him if he thought of a way... He could have put Lips with the band in the final shot of the spring storyarc. During the "twelve days of Christmas" in winter, Rowlf is put with the Electric Mayhem for "six people playing"... They should have put Lips there instead of Rowlf, or put them both in and made it "seven people playing".
When I look at the summer cover and it's obvious that Animal is holding a camera at him and the gang, I felt like it would have been great if that was Walter instead. Seems like something he'd do, and the covers were made after The Muppets came out so it's not like it was done before Walter was created.
There's quite a few original characters who I heard performer voices in while reading. The gorilla's trainer I kept hearing both Frank Oz (his Sam the Eagle voice) and Richard Hunt (his British voice) as. I kept hearing Steve Whitmire as Pops' nephew.