Yes, I know people who installed it.
The whole GUI isn't logically build, and it's hard to get work done. It's also filled with useless junk which is only a resource hog (not talking about programs, about all the services you "need").
All Longhorn is, is a Windows XP skin with a .NET toolbar and a modded explorer.exe and crappy effects that are fun for a while, but which you want to disable anyway to get work done faster.
Saying that no one wants this crap would be wrong though. A lot of suckers are going to love this, not knowing that they ripped the GUI off Mac OS X (effects, design).