A little information about the installation process might help members who are concerned, so I'll try to provide some information during some test installations here.
Today, I downloaded the Windows 10 May 2019 Update in its ISO form and created a USB and a DVD to be used on various computers. My first test is an older Sony VAIO Ultrabook which had a fully updated version of Windows 10 Pro Version 1809 installed previously. Before installing the new update/upgrade, I uninstalled the third party antivirus which was on the computer, ran Disk Cleanup, and defragged the 500 GB hard drive. Next, I copied the update ISO to the "Downloads" folder, mounted the volume and ran "setup.exe" from that location.
The installation went much like previous major update/upgrades and took quite a while to finish, although all things went smoothly with no hiccups. After the computer restarted multiple times and I was able to access the system, I reinstalled the antivirus program, and checked for any more Windows Updates which might be available (a new NET Framework update and a Flash Player update were detected and installed), and I hunted for a few things which might be interesting. I'll list a few of the items users will need to check when the install is finished.
1. I previously had disabled driver updates from Windows Update. The new install changed the setting back to its default (not what I wanted) and I needed to re-adjust those settings to my preference, both in Control Panel-System-Advanced System Settings-Hardware tab-Device Installation Settings and in Group Policy Editor.
2. Here, although my preference is to enable System Restore on the C: drive, the upgrade install disabled it. This happened on the last major update/upgrade also and I once again, had to re-enable System Restore.
3. In addition, there has been a change to the way Chkdsk runs. After making all of the previous changes mentioned above, I'm now in the process of running Chkdsk. Although it works as it's supposed to when using "chkdsk /f /r /x", the new version of chkdsk displays more like previous versions of Windows by showing the process percentage and the stage progress. A nice little touch, I think.
That's it for now, but I'll try to keep you updated on things I'm noticing.
Hope this helps.