Yeah, he got that mask when he almost died in training right? Really weird. Byakuya didn't even know what it was, but he did say it was another entity or something. My reaction when I saw it was "Wow! What the hell is this?"

I like the way the fight ended. Byakuya's sword got destroyed, so nothing left to do.

But the real question I want answered is: Does Ichigo have yet another power move that Zangetsu hasn't gotten around to teaching him? Damn, is this the move that finally collapses the ledge?