"You can look stuff up on the start menu without having to switch back and forth"

You don't have to switch back and forth to look up stuff. Windows Explorer has a search box. You can pin it to the taskbar on your desktop. You can even save searches under Favorites. I have one called "Find Programs" It grabs all "*.exe" in c:\Program Files and all subfolders and displays them in a window much like Start > All Programs > etc..
I prefer jumping back to the Metro style screen because I can check in on the live tiles while I type "Exc" to call up Excel for example.
In my opinion, it's faster than the old start menu. (Start > All Programs > (scroll down) Microsoft Office > Excel).