Ok, so no one liked that joke. Fine. I'll be helpful anyway!
My desktop install of Windows 10 (a clean install of Windows 8.1 then an immediate upgrade to 10) went smooth. My old laptop (a.k.a. the Brick) not so much. Here's what I've learned:
If you have issues with Windows 10 getting stuck (usually at 99% after hours of installing), make sure you have an Anti-Virus program that's both compatible with Windows 10 and turned off for the install. Mine had some Symantec offering that, even with everything off and disabled, STILL was quarantining install files...

It's now removed from the system. Next, change the Windows Update service to type "Manual" (in Control Panel, Services) and stop it (using Task Manager, Processes). Reboot and try again. An alternate way (to the reboot method) is to kill the process SetupHost.exe. After a bit, the Windows Upgrade Assistant will put up a window saying something went wrong with a button to try again.
That's where I've gotten to so far... It's trying again as I type this.