To paraphrase, I didn't really like this episode and that's because of two main issues I had with it .

First, it seemed like a rehash of stuff we've already seen. I remember in the manga there were two parts of Bleach chapter 0 which covered Renji finding out he was getting promoted and Rukia being assigned to the living world as well as something about Ichigo talking to ghosts. However I seem to recall that stuff being animated near the end of the Bount arc or something so I felt like half of this ep was essentially a fleshed out repeat of previosly aired material (Bleach isn't Haruhi and shouldn't try to act like it is).

Second, it seemed like they wanted to make Mizuiro seem like an important and interesting character when he has effectively been dead weight for 227 episodes. I think he's supposed to be the Tsukkomi to complement Keigo's Boke ways but the entire cast is already Keigo's Tsukkomi so Mizuiro isn't really brinigng anything new or special to the table. He sometimes provides stimulus to make Keigo go more insane but it doesn't seem like Keigo actually needs Misuiro in order to go insane, he can just do it on his own and then one of the main cast members can shoot him down.

That said, I am mildly interested in where they'll go from here. I had the idea that they could spin this into a 'what if Ichigo never met Rukia or what if Rukia met Ichigo but never got hurt to the point she needed to give him her powers' alternate retelling of the first season. I would actually be interested in seeing something like that.