Everything should continue to work fine as long as you upgrade all of the backend infrastructure.   I waited a couple of days before I upgraded agents and clients in my environment and had no reported issues.

If your using linked clones you will want to update the parent image and push it back out instead of trying to update individual clones.   Of course full desktops will have to be updated one at a time or you will have to use some sort of delivery method to upgrade them.