I got the notification yesterday so decided to use my laptop as the guinea pig before upgrading the main desktop system.
I have to say was reasonably seamless, i had no major issues & it basically gave me back my pre-existing desktop with the addition of the sidebar.
What i did find however was that i run kaspersky protection & i had to download the compatible update separately for it, as it has disappeared completely. Not a big deal though just another 15-30 mins stuffing around.
Like anything new will take a bit of getting used to menus etc, but will persevere on the laptop before upgrading desktop system(my main business machine).
The other thing i did notice was that it would seem iTunes has been give the flick, but may just have to download an updated version & it also seems a bit sluggish so will have to upgrade the ram me thinks.
Generally though hasnt been a drama & the MS browser is Shitloads better than the old ie