If you're in the Windows 10 Insider Preview Fast ring, chances are very good you're now running build 10586. It's stable, it matches what we've all been expecting from the "final" version of Windows 10 Fall Update (somebody please rename it to Windows 10 November 2015 or something a bit more suitable), and it's very likely to replace the July 29 RTM version, build 10240, in the coming week.
The telltale sign: There's no build watermark on the desktop of 10586 PC -- "Windows 10 Pro Insider Preview / Evaluation copy. Build 10576" no longer appears. As I mentioned last week, that's a clear indication Microsoft intends to make this the one and only.
In my overnight testing, I couldn't find a single thing that's changed in the interface from the previous Insider version, build 10576, which arrived Oct. 29. Even the obscure Insider ring choice (Start > Settings > Update & Security > Windows Update > Advanced options > Get Insider Preview builds) is still a slider. From a user's point of view, 10586 = 10576, as best I can tell.
That reflects a week in final sprint mode -- none of the changes are visible, they're all the happening under the covers. It looks like the Fall Update is baked.
When it comes to rolling out the bits, there are several differences between this release and the original RTM release on July 29. For starters, Microsoft will have to upgrade 120 to 130 million users this time around. There's a whole host of documentation that should arrive for such items as changes in activation method (woefully missing from build 10240), the new Windows Store for Business, any improvements to the Windows Update for Business blueprint (which, I'm guessing, won't become an actual software product), and procedures for the Long Term Servicing Branch. Even Brandon LeBlanc has promised an update on high-resolution features in Win10 FU. Expect a deluge of blogs.
Perhaps that's why we're seeing a change from the way RTM build 10240 rolled out. Build 10240 was released simultaneously to both Fast and Slow rings. Build 10586/Fall Update is Fast ring only at this point (sure to change shortly). Build 10240 appeared two weeks before it went out to the world at large. I have no clue when build 10586 will appear in the RTM coerced-update queue, but I'm still betting Microsoft won't make it by Nov. 10, which is a traditional Patch Tuesday. Will it take two weeks to move from Fast ring to general distribution? Unlikely, but it's anybody's guess.
All in all, Microsoft has managed to squeeze about three months' worth of development into about three months -- which is great, but it isn't the significant "Windows as a service" quarterly bump many of us anticipated.
In traditional, old-fashioned lingo, I'd say the Win10 Fall Update is less than a service pack and more than an update rollup. The apps have been upgraded -- in some cases significantly -- but that's analogous to the old Windows Live packages getting some grease.
Tellingly, it appears we won't see another bump in Windows itself until the middle of next year, when Redstone may (or may not) add compelling new features. One can only hope that some of the Win10 components -- I'm looking at you, Edge -- will get updates before Redstone arrives.