^ I would absolutely concur with your point about the change in Michael. He is, largely, my biggest compaint about the new season. It's one thing to see him having fallen from grace but the way he behaves throughout the fifteen episodes leaves a lot to be desired if we're supposed to be rooting for him the way we did during the first three seasons. I'm willing to let that one go though, because it's painfully obvious the ending of season four was specifically laying ground for the film/season five conflict between Michael and his son with the family in the backdrop as they all come back together.
I was willing to subscribe to his criticisms until I reached the following paragraph:
The key with any sequel, whether it’s The Godfather II, The Hangover II, or Indiana Jones & The Temple of Doom, is to think about the promise the original made to the audience, and to deliver on that same promise, in a slightly different way.
All three of those movies (with the possible exception of The Godfather Part II...) don't come close to comparison with the original films. Especially in the case of Hangover Part II and IJ: Temple of Doom, when both of those films are barely shadows of the great films that preceded them.
And, on top of that, I provide counterpoint: Aliens. A film that completely upends the "engine" of its predecessor, and ends up being the superior film. (I note that this is a contentious opinion, however).
All of which is subjective. I love Aliens, Godfather II, and Temple of Doom but Hangover II is, in my opinion, garbage. So what? All it means is that this system works some of the time and not all of the time.