I've got the KotS, and I'm currently prepping it for play with two separate groups of fellow gamers. The pre-ordered books are waiting in the wings......
I feel great about 4e.
Why wouldn't I? You can teach an old dog new tricks, after all, despite what they say.
After playing the demo, delv, and adventures based on the collected rules here on ENworld, my opinion on 4E came full-circle (i.e., create/find a campaign while continuing in my various 3.x games).