Is Leopard Apple's Vista?
As I write this, I'm installing Leopard on my Mac Pro, having used it since release on my MacBook Pro, so you can take that as my firm "no" vote.
Here's what's wrong with Leopard as far as I'm concerned:
1) The translucent menu bar is a bit ugly. I think I'll use a command line hack to fix it.
2) The dock with reflections (on the bottom of the screen) looks stupid. I've moved my dock to the left side of the screen, which works well and looks fine. I should have done it years ago (when I started using 16:9 aspect ratio displays) but Leopard forced me to do that, or use a command line hack to fix that as well.
3) Until 10.5.1 came out, my MacBook wasn't going to sleep properly. Now fixed.
Aside from that, Leopard has three compelling features that I was missing terribly when using Tiger:
1) Apple tweaked spotlight to work as an app launcher. I far prefer the improved Spotlight to QuickSilver. If OS X were open source this would have been backported to Tiger, but Apple prefers to make money. Oh well.
2) Stacks are great (if I could customize the icon of a stack they'd be perfect). They finally eliminate the need for something to replace OS 9's wonderful but flawed tabbed Finder windows and the Apple menu, and they're better than either.
3) Spaces is the first virtual display solution I've ever not given up using after a week. The ability to have apps automatically launch into specific workspaces, integration with Expose, is very good (not perfect).
Here's what's great about Vista compared with XP:
Nothing, although I do prefer Aero to XP's default theme visually (there's a low bar). I find the blurry window frames very distracting and ugly, and running Vista the laptop I use it on runs hot if I open a text editor.
Here's what's wrong with Vista:
1) Sluggish waking from sleep.
2) Idiotic confirmation dialogs.
3) Idiotic automatic updates are basically about as bad as having viruses on your computer installed by the Vendor. Only you could clean viruses off your system; this crap is working as intended.
I don't hate Vista. I don't prefer XP. Both are pretty decent ... for Windows.