Handstand was always fun. I remember being surprised to see him do it the first time because it's not something I'd have expected from a ninja character's typical movelist... some people I played with joked that he was breakdancing, lol. Never would have thought that a move that you could be so silly with could turn out to be so useful. It's a unique "stance" among fighting game characters in general, really.
Master aside, there is only one Hayabusa player I know that does this. The rest is a mystery. Like how did you get in high ranks without even using the handstand? That and the absence of the Izuna Drop and P+K, P,P, 360T as a combo ender!