I think the did something really ambitious here and if there really were scheduling difficulties with getting the whole cast together for filming i applaud Mitch as much as I possibly can for taking the time to come up with something so involved and clever rather than sticking to the same formula.
However, I think there's two things that made AD special. First, how fucking clever it was, and second, the interaction between Michael and the rest of the cast. Season 4 is way high up in the first category, but I think kind of lacking in the second. Maybe that's just a necessary evil because of how they were forced to film things.
Still though, I found myself enjoying any scene where Michael and Gob were on screen together the most. Those parts brought me back to that family interaction that was part of the old seasons.
Another minor complaint, I think they made Michael a little too dumb all around. He was always quirky with how he treated George Michael as well as how he was around women, and I understand those were pretty much his two main story arcs in season 4, but it's still kind of weird to me that he isn't the relatable rock centering things like in the past.
So I definitely think there are some things missing from season 4, but the creativity level alone might outweigh that even. Toss up between this and season 2 for me though. 4 might be the most consistently funny batch of episodes but I think 2 ended with some of the best TV comedy of all time.
The last 4 episodes of season 2 were:
Sword of Destiny (Tony Wonder, Buster/Gob Use Your Allusion)
Meat the Veals (You have to lock that down)
Spring Breakout (Zach Braff, surfboard)
Righteous Brothers (Franklin Comes Alive)
I don't think this season tops those four episodes, but as a whole it was pretty amazing. I was in tears during the two Gob episodes.