I LOVE the stance changes, they're really nuts! My only exceptions would have to be for Bullet Dance (never liked the backwards roll attack in the first place), coiling viper basically only having 2 combos (unfinished?) and the Nikana stances restricting movement heavily. Unlike the opinions I've seen stated here, I love that the w combos let you move forward freely in almost all cases, it's intuitive. If you're holding forward while attacking, it's natural to expect to be able to move while doing so, right? Nothing frustrates me more than holding forward while attacking and going... really... slowly... forward... while locked in an animation. That was a big problem with the previous melee iteration that you've completely fixed here, and I appreciate it.
There IS something I'd like to point out about the new heavy attack system- maybe if a heavy attack misses, it shouldn't consume the combo counter? That's just a suggestion though. I like how much faster you build up the combo counter now as well, it lets you hop into a fight with more confidence.