I have Windows 10 version 1809 and it is working perfect.
Windows 10 1903 May 2019 Feature Update has recently appeared on my updates as an optional "install when you are ready" update. It is kept in permanent suspension from normal updates.
Checking the web on this Windows 10 1903 May 2019 Feature Update, I find that even experienced users have had a lot of trouble downloading and installing this update and trouble thereafter with auxiliary programs failing.
Complaints of frozen downloads or installs, being stuck at incomplete for many hours and having to attempt a traumatic restore of previous Windows, plus more problems.
Some have installed it without trouble and it is working well. Who Dares Wins ?
It depends upon your individual PC, device and set-up.
My decision is to put this update on ice until such a time as it has been officially cleaned of trouble by time, feedback and Microsoft updates and auxiliary programs have had time to catch up and become compatible. After the October 2018 debacle with Windows 10 Feature Update 1809, I am going to tread very carefully, observing the golden rule - If it 'aint broke, don't fix it..
2 - 4 months delay in installing 1903 should be adequate for debugging.
Windows 1903 incorporates a sandbox, which may conflict with users who use Sandboxie.
Windows 10 version 1809 end of service life is May 12, 2020, so there is no rush to install 1903.
End of service life for Windows 1903 is December 8, 2020.
1903 is a massive OS Feature Update - https://tinyurl.com/y4jua2lj