I've been in a couple of conversations lately on the merits of Windows 8's Metro UI. It's an expansion of the Windows Phone UI, of course, and I've been using that since it's initial release in the US. I'm quite in love with the Start screen for both OSes. Back in the day, I was a huge fan of PalmOS but the world has, of course, moved along since then. To this day, there's no mobile OS out there that provides the quality PDA experience that Palm did. (And while I'm at it, you disrespectful kids need to get off my lawn!) When I see the raves about iOS, I don't really understand them. It's pretty, but in so many ways it's not much different than PalmOS. The "start" screen is a collection of (almost) static icons organized in pages, just like PalmOS was. There's nothing wrong with that, but I just don't see how it's as magical as many people say.
On the other hand, with the Metro-style Start screen, you've got tiles that have the ability to give you real bits of information at a glance. It's a great phone experience. I've been using Windows 8 daily since the consumer preview was released and I think it's a wonderful PC experience as well. It could still use a few tweaks, of course, but Microsoft is still making those tweaks and will probably continue to do so even after the release preview hits.
I'm looking forward to seeing Windows RT on a tablet. It's my opinion that the experience will blow iOS on the iPad away. The live tiles, the sharing of Metro apps between the tablet and desktop, MS Office apps included in Windows RT -- all point toward an offering that's going to compete quite well with Apple from day one, assuming there are some decent tablets out there at launch.
The big thing working against Windows 8 is people's resistance to change. Metro is a different experience. It looks different, if feels different, and it doesn't matter that, at least in my opinion, it's a better experience. It's different and a lot of people are going to dislike it for that reason alone. There's a long history of people disliking changes in the Microsoft desktop ecosystem. The change from the Windows 3.x program manager to the Windows 95 UI wasn't universally accepted. The cartoonish look of Windows XP had its detractors. The move to a more secure OS with Vista was almost universally panned, and I'm sure the glassy look wasn't loved by all. The ribbon UI was hated. Yet each of these changes represented an improvement to the ecosystem. It's entirely possible that Windows 8 will receive the same kind of hate that Vista did; however, the UI changes aren't going away any more than the Vista security changes did when Windows 7 came along. Those security changes were necessary and are generally accepted now as a good thing. These UI changes are also necessary and I think they'll be accepted, eventually, as another good thing.
I think the complaints about Metro on non-tablets are a good thing, even though I don't agree with some of them. Pointing out the shortcomings is pushing Microsoft to fix them. Anything we and they can do to make the final bits a great product helps everyone. The changes from developer preview to consumer preview were huge. I expect the changes from consumer preview to release preview to be pretty huge as well and to be based on feedback to the consumer preview. And I also expect the same from release preview to RTM. I'm looking forward to the ride.