While doing some work a couple of days ago I went though the installation of the Vista RC1 build on my older laptop, a Compaq Presario 2800 (yes, an old beast). Mostly it was click, click, wait a lot, so it didn't interrupt me at all.
My installation experience was far better than Scott's, though that might have been only because I did a clean install and not an upgrade (I never do an upgrade of windows; ever). The install went fine, and was faily painless; taking about 1 hour total.
That said, Vista is pretty much horrendous on this machine. It runs, but is very slow: lots of paging and disk activity going on. Also, since it has a very old Mobility Radeon 7500 chip, which pretty much has no graphics acceleration support on Vista (heck, it will BSOD just trying to run the Performance Rating thingie), the whole UI feels fairly sluggish. That said, it's good enough to play Mahjong, which I think might just be my favorite vista feature so far :-)
Perhaps I'll get some time on the weekend to try it on my main laptop and see if at least this time video works as it is supposed to.