Let's give Microsoft a little bit of credit
They've not done what pretty much every other phone manufacturer has done and simply copied the iPhone interface with its layout of icons and favourite applications.
As for mandating things - yes it can be restrictive, but look at the current mishmash of interfaces on S60, Windows Mobile and worst of all - Android. Get a new phone and you wonder where everything has gone.
I don't know why, but I really can't wait to play with the Metro interface - it looks - fun. If you've ever played with a Zune - guess I'm talking to myself here - the interface is fabulous - much, much better than that on the iPod.
There's a chance Microsoft have actually cracked it this time.