It's funny - GNOME 3 looks great but doesn't do what you want it to do, while KDE 4.x looks god awful yet is the most full featured of any of the desktops.
I wonder when they'll realize that those intrusive glow effects are just not cool and come up with a sensible default configuration.
I agree that the default theme and the glow effect are unpleasant, but once I've switched from Air to Oxygen (Workspace Appearance -> Desktop Theme -> Oxygen) and removed the glow (Workspace Appearance -> Window Decorations -> Configure Decoration -> Shadows tab -> uncheck 'Active Window Glow' box), things suddenly look a lot nicer.
KDE, even using default configuration and themes, looks much better than the screenshot in the announcement.
The screenshot is taken with compositing turned off and a bad resolution.
Disclaimer: Im a KDE contributor.
Sorry Emil, but that shot does have compositing enabled.
I'd say it's not the compositing/effects, it's the spacing and general layout. KDE apps tend to look quite cluttered and claustrophobic, at least when I compare them to e.g. OS X and some better GNOME apps. A bit more whitespace wouldn't hurt, you can't fix that with gradients and transparency.