Now that Leopard has been released, we can now talk about our experiences with it fully - whereas before we were limited by the pre-release non-disclosure.
So the good news so far: Performance is good: Intel machines and PPC alike get more responsiveness in the Finder. It's too early to tell whether or not the applications are much faster with the final release, but my guess is that they may be here and there, but not a lot generally. Interface wise, there's a lot of tweaks - useful things like spaces, a new dock - but we'll review those separately. What most people are concerned about right now is "Will it run my old software?"