After upgrading to iTunes 11 and immediately dumping it to revert to 10.7, I've been biding my time, hoping against hope that Apple might respond to the wave of complaints about the dropped features. Or, more likely, a third-party developer would figure out how to script a replacement for the easy, previewable, editable random glory of iTunes DJ, which I use every day of my life.
I've refused to upgrade to Mavericks, entirely because I'm still using iTunes 10.7 and have no desire to "upgrade." Every week the App Store app bugs me to upgrade, and every week I selectively install any other apps or security updates and ignore iTunes 11-point-whatever.
Now with the announcement of Yosemite, it seems that I'm going to be two full versions behind the current Mac OS. But it won't be the first time that some new "feature" outraged me so much that I passed over an OS upgrade (killing Sherlock for the first version of Spotlight was a deal-breaker for me).
Since I bought my first Mac in 1985, I've been a loyal Apple customer. This iTunes misstep isn't going to drive me away from the Mac or iOS, but it sure bugs me, and I'll stick with 10.7 as long as possible—probably setting up a "music server" (similar to my printer server, running an old version of the OS so I can still print to my Apple LaserWriter 16/1600).