Is there anything particular that you are looking for in a home user experience?
I use XP Professional at work and at home, but really what I'm after are 2 different experiences.
At work, I want to be able to get under the hood, tweak around with settings I need, configure services etc. In this way, I don't appreciate the softly-softly approach of Windows trying to protect me from myself! i.e. "Ooh, please don't go in this folder as it has important stuff in it!" or the redesigned control panels...
Whereas in a home setting, these simplifications and abstractions make sense. Presenting a web like interface with all the settings and configuration therefore makes sense, and it does in XP
So, what I'd look for in Longhorn is a distinct separation between editions...if you're using the "Pro" or "Advanced" edition, expect little help from the OS. If you're using the Home edition, expect a more friendly and forgiving experience.