I did that this morning, but not before also installing updates for Windows, Office, VMWare Workstation, Adobe Reader and Multisim. Unfortunately things didn't go as I expected.
Before the reboot, the new version of ESS was working. After the reboot: Error communicating with kernel.
I used the uninstaller in the startmenu hoping to do a clean install, but it couldn't delete everything due to some "insufficient privileges". After a reboot, ESS was no longer in the startmenu and also no longer in the list of installed programs/updates, but it was visible in the systray and listed in the services-list. Then I tried to install the new version again, the installer gave a couple of "insufficient privileges" errors when overwriting files and it was not able to stop the ESS service. I stopped the installer, got the ESET removal tool which I used in safe mode. After yet another reboot, ESS was no longer running (as expected), but when I started the installer again, it said there was already another installer running. Not long after that the new version of ESS suddenly started and requested a reboot.
After yet another reboot, things seem to run as it should. Now I'm hoping it stays that way.