Purchased LR6 (perpetual license) as an upgrade (from 5.7) yesterday, used it about a half hour, and promptly uninstalled it. Switching to crop mode about drove me crazy. Each time I switched in or out of crop mode, the previous frame and the right side editing bar (normally kept hidden) would flash on the screen. Also couldn't deal with the spinning wheel each time I'd go to a 1:1 preview, especially since I had already set up 1:1 previews when I did the original import. Very annoying. Went back to 5.7.