I don't think there's enough in the teaser to judge how valuable it'll be, but what they have shown looks good to me.

The app store is an obvious step, but I don't see OSX ever becoming closed to buying software other ways as on the iOS devices. If they did that they'd be cutting off their nose to spite their face, especially in the commercial sector, I think, though I can't see much of a problem from my point of view if they did.

Plus, the app store isn't a Lion feature as such - it's coming soon separately.

Full screen apps looks good, especially for those of us who use smaller screens. Not compelling on it's own, but good.

Mission Control again is an obvious development, though I still don't know why they wont let us close windows and/or apps from there (black cross in the top left of the preview like managing widgets).

Launchpad is the most exciting one for me. There are ONLY two things I miss from Windows, and one of those is the start menu. Not the actual menu, but a way to organise my apps into logical categories without having to move the actual apps around in the Finder, so this looks great.

Mark

"Not the actual menu, but a way to organise my apps into logical categories without having to move the actual apps around in the Finder »

And you don’t like using aliases to do that?

No, because you have to create them manually. The good thing about the windows start menu is that the aliases are created automatically, and then you just drag them to organise them without affecting the actual apps.

I don't like the actual start menu, just the fact that a system exists beyond a linear, non organised dock and then a folder with all apps in it, and launch pad with folders gives us that.