Before I get hate mail.  Let me start off with that I am a developer, and while Metro is cool and great for your average mom and pop that opens maybe an average of 5 different applications in a week, I open probably 10 times that amount.  (disclaimer, estimates where pulled completely out of thin air for effect)

After I install Visual Studio, SQL server… and many other development software my metro interface has 100’s of tiles.  On a 1920 x 1200 screen resolution monitor I have can scroll four times from end to end.  On top of that at the time of this writing I am not aware of any development software that runs in metro.  So this means that you are always popping to the desktop.  Search is metro only (windows key + F), blink between the two screens a few hundred times a day and you will have one heck of a headache. 

Start8 from Stardock appears to offer up a great free solution (hopefully it stays free)

What it does is adds the windows start button icon, then miniaturizes the metro UI and looks like this:

The other nice thing about it, it gives the option to boot directly to desktop. 

The full metro and boot to metro can be restored by right clicking on the start button and unchecking the options.