I tried it initially under Snow Leopard with a scroll reverser and found it nice on the trackpad, but as a lot of you say, horrible on my mouse's scroll wheel. I switched it off and used normal for ages. Then as the release rumours got going, I decided to try it again on Snow Leopard on my trackpad and mouse and although it felt really weird on the mouse at first, once you get used to it, it really does feel more natural.
You drag the page instead of a scroll bar with you finger(s). And as the scroll bars aren't there most of the time, it works better still, as you don't think about the scroll bars.
P.S. The scroll bars won't disappear by default when you plug in an external mouse with a scroll wheel. You can set them to show "when scrolling" in the "general" system preferences.