I just got Windows 10 Version 1607 (KB3150513) along with the usual defender, malicious software and adobe updates. On both my newer laptop and the slightly older (and retrofitted on top of 8) HP Envy, the “getting windows ready” screen spun for about 15 minutes before the percentage completed updated and restarts resumed.
But Microsoft has started rolling out a more radical change, the Creators Update, build 1703. Ars Technica has an analysis of the features, many of which matter only to gamers or very advanced visual developers. But there are also more security features. The update can be expected to take even longer, especially on older devices.
Less experienced users will not want to take the time right now for such a massive change that could make some devices unstable. Microsoft will roll out the update, with a privacy settings warning (to save them, as the update overlays them with defaults), to newer devices first. I would think many users would have to accept the update by the second week of May. There is a defer option on Professional operation systems but not on the Home edition. There are details here, or here.
The Verge also has a major story here.
Update: April 16
The update popped up (after privacy settings reminded) today on the newer ASUS. It will allow me to delay the Restart for seven days. The shut down and restart options now allow restart without update. (In Windows 7, Updates after shudown have happened sometimes even without being told they will happen.)