That Arrancar that studies Arrancar seemed like he might turn out to be pretty interesting. But he lookes completely human to me...unless I missed something. I don't remember seeing any kind of mask or marking that would suggest he was one. But when I first saw him I started to think that it was Ishdas father. That would have been a twist lol.
The chapter was not as action packed as some of the others (sorry Uno_Caste) but I think it was done to lay the ground work for bigger things. Especially when it comes to the "research" that is being done on the arrancar. I couldn't quite follow the fight with Ishda and the female arrancar, but it seemed that Ishda was at a distinct dissadvantage. I get the feeling that he'll pull it out (as they all will, probably) but it makes me wonder how well they will do against the Espada. If they struggle against the fallen Espada can they really expect to beat the big boys? Especially when its 10 on 5? They will barely be able to escape with Inoue even if Ichigo could go hollow for a full minute.
Speaking of Inoue, they have not shown us what shes been up to for a while. I wonder if she will really get a chance to carry out that plan she was thinking of. Aizen seems to have a good understanding of her powers and is a tactical genius. I wonder if he has already thought of the possibility of her doing something like that.