I'm really curious to see why Tousen decided to join Aizen. Was all his talk of Justice just a lie, or does he follow his own code of Justice that Aizen could possibly fulfill? The thing I don't like has already been mentioned. Gin has been turned into a lapdog, not even attacking Ichigo because his master didn't say anything.

As for Urahara, I wonder why he chose Rukia of all people, and devised the plan to bring her to earth and give Ichigo her powers. That part seems very unpredictable. Perhaps he somehow knew Ichigo had the power to become a shinigami, and set up a situation where Rukia would have to sacrifice herself?

I said it before, Ichigo's Hollow is his own. It didn't come from Kaien or Rukia. There is the question of whether Aizen knows of Ichigo's Hollow form though. Does he know that Ichigo found a way to overcome the barrier on his own?

I really liked human-Mayuri. I'm glad they kept that creepy voice the same too.