>Unless there's some specific difference I'm not aware of, what you're describing is the same install/upgrade process that MS has had for years.
>

I must have avoided the upgrade process by buying new machines, so this was my first.
It's disgraceful.
If you and I delivered apps like this to our clients we'd be out of business.
I did two upgrades- once for my laptop- a very fast Dell- and once for my desktop, a real Dell blazer.
I finally went to sleep while the laptop process ran. It had been running for over 4 hours.
I don't know how long it finally ran
The desktop was faster, but not much.

In each case, the process just paused in place for as much as an hour with no indication of what was happening.
If any of my apps pause for a much as two seconds, I give some kind of indication of what's happening, because clients get jittery and start pressing buttons that cause problems.
The progress % values bear no relation to the actual times elapsed vs the time remaining.
They're not even close.
Why bother?
They'd be better off just showing moving dots, or something like that, but really.. can't they get that right???

At least 3 reboots were required each time.
These are the people that make the OS.
Can't they figure out a way to get an OS installed without 3 reboots?
I ran a Unix installation for 10 years and rebooted that sever twice all that time.
Imagine delivering an app that required 3 reboots and then trying to collect from a client.

The reason that Apple is killing them in the marketplace is that no one at MS is demanding perfection.
Good enough is good enough.