The changes to Tao are really difficult to judge since the way certain Japanese players play her *cough Tsujikawa cough* is at such a high execution level that I can't really comment on her full potential.
Valk is so very much like Slayer in terms of playstyle. Still think he's stronger than what Gates and Lythium say of him, but with no real way to prove or even test it I'll just leave it at that.
Thanks, but that doesn't tell me anything about what to expect for Platinum. I mean, is she rushdown, zoning, Schrodinger fu, okizeme, etc.?
I don't know what Schrodinger Fu is but here's what I think to expect from Platinum so far.
Most people have pointed out the combo of May, Faust, and Zappa. Personally I don't see the Faust in her anymore, other than some of her items are Faustian. Also I dunno if you're familiar with GG. So...
She looks to have basic pressure strings with decent but not very long ranged normals. She doesn't seem to have a normal overhead so her mixups will probably revolve around her command grab.
If her opponent can keep her away (or gets knocked down, or whatever) then she'll look to pressure with her random summon projectiles. With someone locked down by projectiles you can then add jump-in pressure to your offense, which is kind of like an overhead mixup. Also one of her summons seems to add a mixup.
It doesn't seem like it would be too difficult to zone and keep away until you get the summon you think is best for offense given whatever matchup you're in. Tough to really say what her non-offensive gameplay is like without actually playing her or seeing her extensively.
And, of course, keep in mind that things could change since it'll be a while until we actually see her. Also, if you want more detailed info on everything Platinum the best source of info on her so far seems to be this blog:
http://kalfisquine.net/blog/?page_id=843