Ok, well, to the OP I will offer my comments & promise to not be overly techy. Many folks who have spent a bit of time @ this forum, already, know my feelings but, that's ok...
I have been using Windows 8 for about a year. I beta tested it for Microsoft in a dual-boot with Windows 7. I then migrated to the GA & said "bye-bye" to 7. I knew quite a bit of it/about it prior to beginning to, actually, work on or with it. It didn't come as a shock to me, much of it had me keenly interested and I had no prolonged agony learning it, that part took very little time or effort.
Yes, we have turned a corner on the computing road. It has been a very speedy journey & it's not slowing down as the landscape changes & evolves. Demands, usage, work-force and devices & more contribute to things like Windows 8. Yes things are becoming more & more 'mobility driven'.... nothing bad about that. So, yes, we now have an OS that is happy across multiple & varied devices. One that is happy mobile or not and either Touch or not
. But, one where the 'Look & Feel' is consistent and where everything syncs (or can be shared) easily and well between both devices and Users. An OS with access that a person can take with them from device to device and have the same experience available.
Windows 8 shines in several areas. Security, stability, resource management and usage methodology, speed, connectivity (& collaboration), Feature-set, ease of use, uncluttered, not only cosmetically but, technically, as well. The performance of Windows 8 is blatant, striking & impressive. It's ease of installation & its 'intelligence' in that area is a real delight. That fact the so much is embedded and available & on, by default... Less demanding on End Users.
As for the UI, I won't expend many words on that cus it's so trivial or mundane. Start can be used or not used, can have a slew of Tiles or just one. Store APPs are all 100% optional, too. One can stay 100% of the time on Desktop, anyway, so all becomes a moot or, @ least, very subjective, customizable thing. But, it (the UI) is NOT a problem, slows nothing, makes nothing awkward or arduous. Things are there when & if YOU want /need them & out of your way the rest of the time.
Anyway, it's cool what Windows 8 is, what it has in it, what it can do & how well it does what's asked of it. It is smooth, snappy and slick. Both hardware & software compatibility w/ it are very good. Win8 is good, the best Windows OS to date and an important stepping stone to future computing.
I should include that the design goals achieved that focus on & cater to Enterprise are terrific & likable by that environment. The fact that Enterprise can easily create & build APPs useful to their particular 'house' & workers has definite appeal for business.