For all of OS X's sins against the human user interface (I'm not convinced of the ergonomics of the three round button on the top left of windows still, but I live with them, and the Dock can still be a little odd..), it does pummel Vista's Aero Glass UI which is just a dire, cluttered and confusing UI from what I have used.
At times I found myself loosing track of which window was actually active on the screen, not to mention go nuts over the UAP stuff which disabled access to any of the system until I verified what I was doing (dragging some shortcuts into the Trash).
After about twenty minutes of playing, I had to walk away.
iPhoto is not perfect but I still think iPhoto 6 is a very very smart piece of software that this imitation seems to lack in what it captures, though it's not bad either, just a shame about the nasty Aero Glass UI.
The other thing that is laughable however is MS' DVD authoring package which iDVD doesn't just blow out of the water, but blows it out of the universe beyond
And this isn't just a stick the boot in Windows, Mac zealot post—just the facts that MS has a *lot* to do to get a comparable iLife suite for Windows ready, and secondly, the old UI was just so much more functional in the environments it is intended for, ie: businesses.
Vicky