Meh... on the one hand, this volume has lots of Byakuya, whom I like even when he's being a big old conflicted jerk. On the other hand, it has lots of Mayuri, who I do not like, because he is a demented psycho. He's totally disgusting and gives me the shivers whenever he's on screen, but I think he was toned down after this first battle. I mean, he's nowhere near as bad anywhere else as he is here, talking about making people burn their children, and digging holes in their skulls, then taunting Ishida with a photo of his grandfather after torture. Jesus.
I know it was just filler in the anime, but I find it interesting that in the arc about the Kasumi-Ooji family, the newly appointed third seat of the third squad complains that he couldn't get anywhere in the ranks of the gotei 13 because he didn't care enough about his fellow shinigami to protect them from death. Yet, in this volume we see a man who has risen to the rank of Captain who cares so little about his subordinates that he will throw their lives away without a care. I doubt his research and scientific abilities are really that great that Soul Society can afford to overlook the fact that he is a TOTAL PSYCHO.
Oh, we also learn about Yoruichi's true form here, and that she and Byakuya like(d) to play tag. Whee!