I like the idea of a rolling release, in fact its the exact reason I'm trying out LMDE now.
But I'd be royally PO'd if I updated and was running "Unity" afterwards! Even Gnome3 instead of Gnome2 would be intolerable from what I see of them so far.
So far, LMDE rolling is not really working for me. First update breaks Eclipse, been a bit over two weeks and still not fixed. Showstopper if LMDE was my development system (currently Ubuntu 10.04). I'm having no troubles adaptaing to Xfce and could easily live with it. I guess if its good enough for Linus, its good enough for me!
I'm happy to freeze the UI, its current verisons of fast moving libraries like gstreamer, ffmpeg, etc.and the applications that depend on them, that I hope to stay current with by using a rolling release.
OTOH how do you deal with the debacle of application updates like Amarok 1.4 -> Amarok 2? I was able to find a deb of Amarok 1.4 that worked on Ubuntu 10.04, as a work around, but its a pretty fundamental problem, only really solved if someone steps up and forks the old application version as apparently has happened with Amarok 1.4.