Eye candy, lots and lots of eye candy. The transparent menus are a very cool effect. There are a ton of options for window dressing, one thing I thought was nice is that KDE3 now has compatibility with ICEwm themes. Another thing that sort of surprised me is that KDE some how put theme hooks into non-KDE apps. I am not sure how that is being done it makes for a very clean desktop.
KDE3 is also highly configurable. Keyboard shortcuts are abound and easy to modify. You could break the menu free of the launch bar, and have it one click away like window maker. The taskbar is also very configurable, you could make it any size, width, and length you want, and place it the way you want. KDE3 now has a pager, it reminds me of Enlightenment but with better rendering, and it's more intuitive.
All the KDE3 apps seem very solid to me, I've liked them since the KDE1 days. They just keep getting better. Sorry, no full review -- I just don't have the time. But the Koffice suit, Kmail, and Konqueror seem improved from my limited time with them.
It is probably the most integrated desktop environment I have ever used all things considered.
Downside? KDE3 is huge. It makes this 533 P3 with 128 ram seem a bit sluggish.
screenshot after messing with the settings... [cgi-fun.hypermart.net]