Installed. Up to now, very nice interface. Not too cluttered, not childish either ; the size and colours are right. High DPI-aware. Launches without delay, too.
For those who can’t find the activation : there are two executables and two shortcuts. The main program is Good Sync, not Good Sync Explorer. The Activate Pro command is in the Help menu of the main program, Good Sync.
Exceedingly annoying captcha on this site. You need to clear a zillion images (and wait for them), then Google tells you it can’t reach its server and you have to start all over again.