Here is my short review having never laid eyes on this thing… It’s great. How do I know? Apple doesn’t do less than great. If you have a Mac that can run it, get it.
Like Patrick, I didn't sign up for the developer program to access the developer previews. I am downloading OS X Lion as I write this. And I share the exact same sentiments as Patrick — if you're Mac is able to run it, get it. And maybe get a Magic Trackpad if you're still rocking a mouse.