Moving the pointer into the upper left corner of the screen then down the left edge isn't fast enough for you?
For those who aren't familiar with Windows 8 that procedure displays a list of thumbnails representing all the running full screen apps down the left side of the screen. On my laptop I just need to swipe from the left edge of the touchpad. If you left the classic desktop open it's included in the list.
It's not as fast as just clicking on the other window. If I can see part of the other window, all I have to do is click on it; that's one mouse movement and one click. In Windows 8, that's one mouse movement, a scan through several thumbnails to figure out which one is the right one, another mouse movement, and a click. When I'm doing that every minute or two, that's a problem. But that still leaves the problem that I can't see more than one program at a time. I'm frequently looking at data in one program and comparing it to data in another. I can't do that if everything runs full screen.
From the start screen you can start to type the name of an app you want to open and search will usually display a short list containing the desired app by the time two to three characters are typed. Click the app name to open it. Works equally well with apps that require the classic desktop to open.
And somehow that's better than just clicking once in the quick launch bar, or once one start button/orb and once one the menu? What if I can't quite remember what it's called, but I'll know it when I see it? Then I have to try typing several things before getting it right. Sorry, that's not better.
From what I've seen, the Metro interface is great for a tablet or for someone who uses just one program at a time, but it makes the computer practically worthless for someone who uses it the way I do.