If Microsoft insists on all users having to use the Metro interface I'd say it will be the new Vista. I can't see business desktop/laptop users taking to it at all.
It's obvious that Metro will be superb on tablets but why should this replace the Start button on a desktop or laptop PC? It's far too clunky, rather like trying to control your PC using Windows Media Center.
My advice (for what it's worth) is that Microsoft should install Metro on tablets but offer a Metro free interface (i.e. Windows 7 with the new features) for traditional PCs. Why throw the baby out with the bath water?
I tried the Consumer Preview the other day and had no idea how to run Control Panel or even shut the PC down! It took a couple of Web searches to find out how to do the simplest tasks.
Microsoft PLEASE don't force us to use Metro on desktops and laptops. Give us our Start button back. I'll still want a Windows 8 table, promise.
I have been using the consumer preview since it released and there are definitely pros/cons.
PRO: If you've been using the Windows Phone 7 OS the new GUI is actually intuitive. If not it's going to be a shock to the system.
CON: Average users will miss the 'good old Start button' since the bottom-left corner now takes you back to the Metro interface.
There are already hacks available and more to come, I'm sure, to make it look more like Windows 7.
I personally like how customizable the Metro interface is and believe Microsoft may finally have a tablet OS that will give the iPad some decent competition!