This episode is an underrated gem IMO, the concept is brilliant, it was really fun to listen to the actors and director of the episode talking about how they did scenes twice, it was really done well, though I do wish they would have cut back and forth between "dimensions" more often, so scenes makes sense right away instead off after 10 minutes, minor gripe though, because the concept is still brilliant and well executed.
There were also some great character moments, we get hints of Mack's past, we get May desperation to save Coulson, and Fitz and Coulson hashing out how they feel about the later stepping down...also Fitz threatening a man who can break him in half was just adorable!
I continue to like Mace despite him being such a politician, he asked to get consolation for Gabe, no one ever does that in shield, I think his red tape policy while frustrating, is still refreshing to have around.