Ugh... okay, giving 8.1 a try since I sortof hated the schizophrenia that was Win8 to see what these "improvements" are all about.
Issue #1 - A clean install forces you to use online ("cloud"/MS Live) login credentials as your workstation login. Ugh... I *don't* want my computer tied to any particular online services not of my choosing FFS, and I most certainly do NOT want my OS login tied to my freaking junk email account that I don't give a crap about for any reason!
Workaround: Apparently you can install and force local-only account ONLY if you do the install while disconnected from any network.
Issue #2 - Too much wasted space. I'm sorry, "metro" wastes so much god damn space on the screen. So much fixed real estate that is wasted and unrecoverable, unrepurposable all for the sake of "mobile" devices. It simply doesn't belong on a desktop.
Issue #3 - Well, okay, they're giving us (back) slightly better multitasking ability than Win8 had with the 4 panels, but let's face it... I use Windows like a BUSINESS user uses an OS. I generally have a half dozen or more windows open at any given time, and to go with #2, I utilize as much of my onscreen real estate as I can because of it. Overlapped windows is a far better solution than any sort of tiled window system. Microsoft learned this back with the migration from Windows 3.11 /NT3.51 to Win9x/NT4.0. Why they're going back is a mystery to me.
Issue #4 - Again, a pet peeve of mine, because of the metro interface, coupled with #3, they make it painful at best (in metro mode) to see exactly what the hell is running at any given time on your machine at a glance. Yes, go to the left corner and you get a list with a little preview, but it's not "at a glance" like the taskbar provides. It requires action. It's difficult to see what's running in the background, and because of that it's simply not useful to me.
Now, onto the good side of things... (versus vanilla Win8)
Win8 frustrated me with several half-assed implementations of system management tools, especially where certain functions were duplicated between new UI and Old, but they made it relatively impossible to navigate to either in a clear manner. For example, figuring out where to get to all the relevant administrator settings always took a bit of doing in Metro, and trying to get there via the desktop wasn't easy as well. Worse was trying to do something via Metro only to find that those particular functions weren't exposed, so then you'd have to make your way there through the desktop control panel anyway. 8.1 seems a good bit more streamlined and fleshed out in their administration user interfaces.
The Windows Update mechanism seems a bit more solid. I had issues with vanilla Win8 sometimes stalling updates, to the point where I would ALWAYS run updates from the desktop control panel. Granted there haven't been too many updates yet, but still, it never took too long to find issues with Windows Update for Win8 for me.
Everything else about 8.1 seems solid so far. I'm still not fond at all of this "split personality" thing going on with having basically two different UI's. But if it's what has to be, I might as well get used to it.