Metro is better for the "average" home user, but it's also better/quicker for pretty much anyone, including for work use...
First, look at the current start menu on Vista / 7...
... As you can see theres a VERY tiny space that lists your installed programs which you have to scroll through constantly. What makes things worse is that you have to hunt through folders and sub folders to find something. When opening all these folders it makes the list longer so you have to scroll even more. On my monitors (2560x1600) this really is an insane waste of space as no matter how high your displays resolution is the list does not scale with res and only ever shows
20 folders / programs!
One way to solve some of these problems is to use the old XP style menu's (heres an example when used on Win 8)...
... This atleast makes more use of space - but it's still a total mess to look at, and you still have to search through sub folders, which again makes sub menu's appear, sometimes going down a few layers of sub menu's. It's also awkward when you do have to scroll up and down as the list auto scroll's and sometimes goes past stuff you're looking for. So once again, not exactly great.
Now we have Metro...
... With this it finally uses the whole screen to display software/apps. And this scales with screen res, showing more apps with larger displays, so on my 2560x1600 display i'm going to get a **** load of apps shown to me -
150 to be exact! compared to just 20 on Vista / 7. It's also organised in alphabetical groups with larger easy to recognise icons, plus you can simply start typing and it automatically searches as you type (no need for a search box).
Yes Metro takes up the whole screen (which is GOOD thing) so if you're watching a video it will get in the way, but with these cases you simply pin your most used apps to the taskbar as you would in Win 7. According to MS's stats taken from millions of PC's, 88% of app launches don’t actually originate from the Start menu anyway, they're from the taskbar, Explorer, and the desktop.
BTW the above pic is different from the Dev Preview - MS has improved Metro and the apps screen since then. And if anyones wondering you can get to this apps screen in Win 8 by hovering in the bottom left corner of the Start Button –> Search. Or by pressing Windows Key + S (i think).