Seemed like the update loaded in about 15 minutes, but then when it went to restart I was completely fooled by how long it took. I have a new Retina 5K, and with its fusion drive it has - historically - booted up quite quickly. This restart took so long - presenting a black screen with an active cursor only - that I was certain something was bad wrong and I’d have to take the ‘puter into the shop since a cold reboot did no good.
Then I ate dinner, and came back to find the login on offer.
One thing . . . after that when it finished booting it tried to pick up wifi from a different source than my own router. It’s done that before. Is there some way to make the system smarter than that?