KDE 4.1 is made entirely of delicious eye candy. It's still slightly unfinished and geeky, but remains deeply tasty. As I say that "KDE is like Windows but it works," so KDE 4.1 is like Vista but it works. Which is a bit like "is like anthrax but not bad for you," but anyway.
If you're not willing to geekily beat it into behaving, don't try it yet. But if you are: how to set it up in Ubuntu Hardy (you have to add an experimental repository); install gtk-qt-engine-kde4 to solve the Fugly Firefox problem; install quick launch if you want that (though I couldn't get it to work); switch off single-click launch in Konqueror; reboot; fiddle with all the settings. Play and have fun.