By cons ...
The Metro interface has no place on a desktop computer.
I can understand for a tablet, but generalize this interface has any type of computer is not normal.
Gros backward compatibility problem, I have to appreciate moderately update my Office and Adobe licenses because the versions that I had were not compatible.
Similarly for certain devices, such as a multimedia printer with integrated scanner that can print but can not scan ...
In the end we forgotten that in the budget of the update under Win8 there will not be the price of the operating system, but it will include other software and peripherals, and leaving the note may be high ...