Power consumption slightly down, performance up somewhat though still trailing the 5970.
If the leaked Cayman results are true though it'll really be in trouble. Smaller die, faster, and lower power consumption.
Nvidia really needs to get to 28nm, though TSMC isn't making that easy.
I'm a little disappointed that Cayman XT's TDP is 224W - mind you, Cypress XT with it's 188W TDP only uses about 120 on average. So we'll just see what testing shows.
I think I'll probably stick with my 5870 until 28nm cards come out. Here's hoping that the rumors of ATI using GlobalFoundries 28nm process are true.
Also, it would be interesting if Nvidia started using GlobalFoundries (I think Nvidia would benefit from it).... though that's unlikely.