He's definitely faceroll. Faceroll on that level with early pressure and certainly backs it up with scaling if he was fed.
PBE changes are definitely a buff. And a teeny tiny nerf. Current Xin maxes E for dash cooldown, upfront damage, and aoe on camps. E cooldown is going to 12 flat from 14/13/12/11/10. In exchange they mega buff his Q/W. Goal is to make Q max the thing I think. They're trying to make Xin's Q and auto attacks feel awesome which is a noble goal design wise. He'll remain a faceroll snowbally champion though and will probably start making appearances at the pro level despite being a really direct and cheesy champion. I'm curious how it'll end up. Probably with him living in the ban tier for a bit.