I just downloaded the Kororaa XGL Demo Live CD, and it blew my socks off! Although I'd seen the videos on Novell's website, I was expecting it to be unusable on my machine - just from past experience of flashy graphics on the desktop. But it worked, and it's awesome! It also wowed my non-geeky housemates. It was Gnome rather than KDE, but I hope that KDE will be able to look just as amazing with XGL eventually. I wasn't too keen on the way the menus popped up, but the rest of it looked great.
I also couldn't help liking how clean Gnome was looking. Of course, I wouldn't be able to switch because I like too much of KDE, but I think all KDE developers should occasionally look at Gnome so we can steal their ideas, just as I'd expect their developers to look at KDE and steal ours. Because by 'steal' I really mean collaborate.
Anyway, one of the things I prefer in Gnome to KDE is the way things feel a little more solid and neatly put together. Like when you click on the volume icon in the menubar at the top, the slider which appears is exactly the same width as the highlight on the icon - it makes it look like it was all designed to work together. Whereas KDE I know is designed to work together, but doesn't always look that way.
I just wish I had more time to develop KDE at the moment, but work is taking too much time, and in my free time I'm working on my wedding website, so unfortunately developing KDE is taking a back seat to using it.