>How does the fancy-dancy "aero glass" feel, and how in the way does it get?

The only place I've seen it used is on Windows borders. I haven't really noticed it.

>How well do you think my grandmother would do with the install (she 'uses' e-mail and the internet and that's about it)?

She'll be fine installing, but probably lost using. Menus have been moved around. Outlook Express has been replaced by Windows Mail, but I haven't tried it yet.

>Have you seen anything yet that makes it a very USEFUL upgrade from XP or Win2K?

IMO, the improved stability and security make it more than useful.