I understand the abstract principle behind it, but that does not help.
Two examples I noticed when fooling around with it. Nothing major, but they illustrate the problem very well. This is using a default and clean install of the consumer preview:
So you boot it up and are presented with a big image that displays the time and nothing else. Clicking just makes the image hop, you actually have to swipe upwards (with the mouse!) to be allowed to log in.
You see this PDF in the Explorer and double click it. A Metro app launches and removes all UI elements you just saw and are used to. There is no way to close it on screen, nowhere to click to get out of it. You have to know about the hot corners or keyboard shortcuts to get out of it. Even then: It’s a jarring transition between two completely different UI paradigms. That is no fun even if you know how to get out of it, even if you know that it’s supposed to be that way.
All of this would be fine if normal Windows apps were on their way out. If we all were to ditch our mice. If the Desktop were only there for compatibility reasons, to run those old apps no one is going to use in a year or two anyway. Only, even Microsoft doesn’t seem to be on that path. It looks like Office will not be a Metro app, for example.
I don’t want to see Windows 8 fail. Metro is incredibly cool for tablets and phones. (Windows 7 also was incredibly great – for Windows – as a desktop OS. It works really well.) It’s really awesome! But I’m not sure about the Metro and old Windows UI hodgepodge. I just can’t convince myself that touch interfaces work well with the mouse. It’s just not fun to swipe with a mouse. And interfaces which are fun to use with swipes and taps are not necessarily fun to use with a mouse. (The reverse is obviously also true.) All the Metro apps seem like incredibly cool tablet apps. I can see that I would have a lot of fun with them on my iPad. The Store is also cool and very well integrated. But with a mouse? In such a leaky environment? Where the mouse user is confronted with touch interfaces over and over?
What Microsoft is doing is incredibly brave. That alone deserves recognition. But I really can’t see it succeeding. Maybe I’m wrong.