I think it could be great for tablets and "transformer" type computers but for a mouse and keyboard? Are you kidding?
No...well, I like the Start Screen.
The Start Screen is no different than the Start Menu except it's in the form of a screen instead of a menu. If we step back from are reluctance for change, the start screen that's in the Developer's Preview is likely very different than the start screen in the Windows 8 RTM and likely the Consumer Preview that's coming out in February. I have no problem with the desktop being deprecated to "app" status, which is what it is in the Dev Preview. It just requires thinking differently.
Also, when Windows 8 RTMs (and possibly in the Consumer Preview) I'm sure there will be a way to "hide" the start screen so that the desktop is in the foreground, probably in the "professional/enterprise" versions by default. What you'll lose with by not using the Start Screen is parts of the Windows Store and I doubt business would want their users to be buying apps on their work computers. But, at some point, probably in the near future there will be Metro apps for work, that will require the Start Screen. In "Windows 9", we'll be done with the desktop, I believe.