What iPad has indeed shown is, you can't have lag, jitteriness, lack of feedback and downright unresponsiveness on Tablets. Fanboys are indeed not helping.
I stopped by at Microsoft store on the first day and immediately noticed that Asus Vivo RT (at Bestbuy) is more responsive than Surface RT. But even then, many WinRT apps suffered from bad UX design. I would touch on something in an app and couldn't tell if the App has started doing something or if the touch failed to register. After touching the same app couple of times, the first action would start anyway. The general laginess in almost every app was not good at all.
I want this thing to succeed. But the whole thing needs to be more performant on the ARM processors.
In the end, I kept thinking, why would I shell out 500 bucks for this. At the basic level though, the basic framework (live tiles, charms, etcetra) looks exciting and I like the flow, but things gotta improve .....