Disclaimer: I work for microsoft as a UI/UX designer/prototyper, primarily on Windows's "Metro" interface, so I'm probably HIGHLY biased in this area. But I may still be able to shed some light on this.
I've been using Win8 for about 8 or 9 months now. Originally, I was in the same boat as CowboyNeal - I loathed the new start menu. It felt wonky to scroll through and find my programs. After using it for a while though, I highly prefer it to the old start menu.
The start menu on Windows 7 was great for mouse navigation - short traversals to each entity meant that you could get through them quickly with a mouse. Where it failed though was in keyboard driven execution. Win 7's keyboard launching capabilities absolutely sucked. I wrote up a pretty technical paper on its shortcomings, one specific example was heirarchy of information in search: while trying to launch Dota 2 in windows 7, I pressed the win key and typed in "dota". The first result was an autogenerated xml file that I didn't even know existed on my computer, with "dota" matching a substring of a randomly generated hash. The "Dota 2" program was 14th on the list, despite me opening it often. Because of this, I rarely used search on my windows box. In OSX however, I almost always use spotlight (~95% of the time) to launch anything. Noticing this I decided to give the search in win 8 a shot, as I heard it had been improved. It was vastly better - better than spotlight and probably on par or slightly better than quicksilver. Since the standard desktop is still there, and the keyboard driven launching is actually usable, I just stay in desktop mode and use the metro home screen as a glorified spotlight. It takes some getting used to due to the fact that it's fullscreen, but it has more data on screen at once, which means on the rare chance that I am searching for something more detailed, it seems to be a bit more efficient. That with the speed improvements in 8 over 7 (8 is a lot snappier) makes me prefer it to 7 nowadays. Just food for thought.