Win 8.1 "RTM" is GREAT
Runs great! Nightly, ice dragon, cometbird browsers with 38 tabs, outlook, IE with maybe 10 - 3.2 gig memory used. Boots extremely quickly. Mounts *.iso. Runs hyper-V VM's. Bootleg true MS code installs fine with default key, activates with win 8.0 key. IE can be set to one mode only, desktop or TIFKAM. Tiled start screen manageable. TIFKAM side by side works intelligently. Between new "start" and older WinKey 'power menu', charms can be avoided. Ne search feature now works as they say it did in Preview. Media Center was there.
I don't see much reason to change/upgrade tools 'just because its new', but this thing is a real improvement!
There are issues imho with portable contraptions used as computers, even laptops, but both Intel and ARM chips and SSD storage are getting to the point where before long applications as opposed to "aps" will run and run well. The smaller display and small, non-existent, or add-on KB input means limit the use of such Iimho, but they sure are great for taking ones electronic connections, including the hundreds of thousands of 'aps, with one at all times. And the portables are largely used for networking, geography, media consumption, and communication.
Whether the concept of "one ring to rule them all" makes sense, I don't know. The use case differs. BUT. If it matures successfully, users and those who support them and code for them would have one and only one user interface to deal with. It's already converging - MAC OS X, Android, Windows, and most public-oriented Linux distros are looing more alike every day.
As to the upgrade. I put 8.1 RTM atop a 8.1 preview and yes I had to reinstall the limited number of aps , principally communication, browsers, and productivity stuff. There is no 'keep aps' option on this path, as was stated in the beginning. I AM WAITING for the actual final release code to upgrade 8.0. Screen shots from others who have put the RTM - ACTUALLY ANOTHER BETA - atop 8.0 show a "keep aps" option. Also, the real public release build will be supported for 90 days after install.