I'm not sure I agree that this method of upgrade is neat, keen or even slick at all.
This thing was huge, nearly the size of the initial ISO. It installed as an upgrade, leaving us with about a 3.5 or so GB Windows.OLD folder. And we all know how well most upgrades actually do overall.
AND
If this is the method they are going to continue to use after the final GA release, I don't believe I'm gonna like it any better then.
Rumors are indicating that this will be the last major Windows release ever and that we'll be running Windows 10 for a very, very long time with annual updates like 10.1, 10.2, 10.3, etc., etc.
You'd have to be completely oblivious not to know that in the past, there has been some serious problems with Windows...