I gave up on CapOne at 7 because I hate forced cataloging but my experience with Yosemite has really made me as mad as the upgrade that changed the scrollbars. Yosemite broke the App Store, Kindle, and Thunderbird, made unnecessary GUI changes to Safari, and slowed the Finder. Downloads seem slower, everything loads like a snail. Not happy. I managed to get the apps working, but I had to redownload 400 books, the App Store is extremely slow on updates, and the Finder is doing little weird things.
I downloaded a video/image app that was 84mB and it took ten minutes. That is ridiculous. I have 25 mbps service.