The casual email or web page user might adapt easily to Win8, but hardcore user, used to multi-tasking on multiple screens will resist.
My main complaint with the Release Preview is that I need to concentrate on the software development or system administration tasks at hand, and not have to think about the UI components that support them. I typically have 2 24” monitors, with 15 - 20 windows open that I’m switching between. Win8 does not seem conducive to this.
The casual user who doesn’t play games and just wants to surf the web should use linux, its free too