Why post this now? Partly because there's a Windows 10 version update coming in April, & perhaps more than prior version updates you'll want to have a full backup handy, & because a couple of months gives you time to setup a backup solution if you don't have one already, including time to find a drive to store your backup(s) if necessary.
Windows 10 Creators Edition [as it's called] is feature complete, with bug fixing until probably March, followed by the RTM [Release To Manufacturing], and then the general release in April [to everyone running 10 that hasn't already upgraded to the build through the Insider program]. Feature complete means that decisions are finalized on what's included in this update, & what didn't survive the cut. Stuff that doesn't make it could be included with other new features this fall, when it's reported the 2nd major update of 2017 will occur. [Yup, 2 Windows 10 installs this year.]
The last major update [the Anniversary update or version or build] was considered by many a disaster... the basic idea was sound, delaying the update on any hardware that experienced problems until those problems were fixed, but when the delay turned into months for so many that was just too long & drawn out. *Probably* look for Microsoft to shorten any delays, maybe dramatically.
Microsoft also wants to save some bandwidth -- building on changes they've already made for regular updates, they've changed the way new versions or builds are delivered. Since some future build of Windows 10 -- regular Windows 10 & not just Windows 10 Mobile -- will add support for some ARM processors in 2017, and since ARM processors are MUCH more common in mobile devices, I'd guess more changes could very well happen to make the setup & upgrade processes more mobile device friendly.
RE: Updates, the old way was that when a patch or hotfix was released, new files replaced old, end of story. Microsoft has *somewhat* changed the way that Windows keeps track of which updates had been installed... in Windows 7 you could delete old update setup files using Windows Disk Cleanup, but the next time Windows Update performed a scan [to see what was needed], it could take a Very long time as Windows rebuilt its list of applied updates.
Now Windows checks its update status to install just what's needed from large cumulative updates, which reportedly will eventually include every update ever released for that version of Windows. The penalty for deleting old update setup files seems much less if not gone entirely.
When you install Windows from a setup disc or USB stick it uses an image file that contains most everything needed to install & run Windows. Microsoft designed & developed their .wim image format just for this. There are also .esd image files, which are encrypted .wim files that may be compressed for a smaller file size. An .esd file can be decrypted by the version of Windows it was targeted for, e.g. you need 10 to decrypt an .esd intended for Windows 10. The complete set of Windows setup files [an ISO], downloaded or on a disc, include the necessary install.wim.
Until very recently, when you upgraded Windows 10 versions or builds using Windows Update, a install.esd file was downloaded & used. Not any more -- only those files that are needed are downloaded, rather than the complete set in the .esd. This saves bandwidth because less data's downloaded. That benefit [mainly for Microsoft?] is offset by the work Windows has to do to figure out just which files are necessary.
For Windows 10 hotfix & version updates on lower powered devices, those without more expensive & powerful CPUs, this means a Long slog with often 100% CPU &/or disk use that can render them useless until whatever updates are completed. A VM with 2 cores & 4GB RAM took about 12 hours to upgrade to the latest Insider build, & that VM has hardly any software to transfer over. The next version of 10 will let you postpone updates for up to 30 days, so you have some control over when your device is out of commission, but so far Microsoft says that will not be available for Windows 10 Home.
There continue to be just bad installs of 10, whether a result of the initial installation or updates &/or mods performed later on. I can confirm it's not hardware related -- at one point I had 2 identical 10 installs on this PC, & one of them worked fine, the other not so much, to the point it had to be replaced by a fresh install. With the new method of updating versions or builds, this has become a bit more of a problem.
Windows 10 won't work with some drivers -- a new version of 10 may not work with drivers that had worked just fine with previous versions. When/if you upgrade [rather than installing fresh], the last few Insider builds re-use the same drivers as the existing install, even when they won't work with the new version. Working with a VM, this meant that the new version [build] would start, crash without a BSD or any notice or logs, restart, crash, & so on until it was just powered off. A fresh install, not saving or keeping anything from the earlier version [including apps, settings, accounts etc.], worked because it did not install the non-working display driver, using a generic driver built into Windows instead -- *to me* that hints that Windows setup knew better, but screwed up anyway.
Something that *may* be an issue for some people who download Windows setup ISOs, if you normally burn a DVD rather than use a USB stick, a few recent Insider build ISOs were large enough to require a dual layer DVD. I've no idea of course what size the ISOs for the April release will be. And there's always the free Rufus, a small app available as portable that'll put that ISO on a bootable USB stick. Why bother with ISOs? To turn that 12 hour slog I experienced into something that takes around an hour or so... Just right click the ISO in 10, mount it, & run setup.exe to upgrade.
Another trend I've seen that sometimes makes both regular & version [build] updates take [sometimes MUCH] longer, is anti virus software scanning update &/or accessed files as the update's going on. By default Windows 10 is set to download update files not just from Microsoft but from PCs on your network & over the internet, so I can see where that scanning might make good sense. However, that added virus scanning can stretch the update process by 3 or 4 times [or more!] in my experience. I've seen this with McAfee, Bitdefender, & Windows own Defender.
As in the past, I don't think it's a terrible idea to try one of the Insider builds as we get closer to the April release -- that way if you have problems running the new 10, you've at least got fair warning along with a chance to find a cure or work-a-round, if one exists. You can install it so you boot to a external drive, a VHD, another partition on an internal drive, or after a full backup that you know you can restore, over the top of the Windows 10 you have now. And if you're running 7 or 8, I haven't seen anything about Microsoft finally turning off the free Windows 10 upgrade yet, though it would be a good idea to Google 1st, because it just may not have been reported on the sites I normally read.
