Of course you can, particularly with the Desktop. Yes when you live primarily in the Desktop then the Start Screen is more jarring then the Start Menu was. I would likely pin more things to the Task Bar or put my shortcuts on the desktop to reduce the use of the Start Screen in this environment. But hey, take a look:
And of course you can run a Metro app and the desktop at the same time too:
As I learn new little tricks, for example right-click in the lower left corner of the desktop makes some frequent power-user tasks more accessible, Desktop-style use gets more acceptable. I’m still not comfortable with Windows 8 on a traditional desktop PC, but I only have a couple of hours doing so with the Consumer Preview. Will I hate, tolerate, like, or love it? Only time will tell.