Well, so far so good. I've watched episodes 1576 and 1836, and many of the bonus clips (including everything that I previously hadn't heard of).
I've noticed some mistakes and contradictory information in the booklet. It says that Polly Darton debuted in season 13, while one segment with her is included under season 12, and that song (according to Muppet Wiki) is copyrighted 1980 so the sketch placement isn't a mistake (maybe she started out as a one-shot character and became a regular in season 13). It also incorrectly lists Forgetful Jones as having debuted in season 11, when a season 12 press release said that he debuted that season, though the time says that he debuted in 1980.
After reading the content listing, I started remembering the "in the rain" segment with Maria as Charlie Chaplin. That was great to see again. Interestingly, the booklet for volume 2 includes a trademark credit for Charlie Chaplin's appearance but no such credit is in this volmes booklet (it wasn't noted in the credits of the previous volume).
I assumed "weather around the world" was a film insert, so I was surprised to see that it is actually the sketch with Simon Soundman listening to a colonel talk about his trip around the world. That's actually a pleaseant surprise.
Although there are no Deena and Pearl sketches included, the "Big Hello 1-20" clip does feature Deena. It's a shame we don't hear her talk (ditto with Poco Loco, I'd have liked to have heard the voice Michael Earl used for the character). It's also interesting how the disc 2 main menu has that clip, when the full clip is on disc 1.