Over the years we've seen numerous features, both serious and trivial, removed from OS X in what seems an effort to "dumb down" the operating system. For example, the spinning time machine icon used to spin when backing up at least giving a warning to a user that a backup is occurring so maybe now is not the time to shut down your system. The removal of expose and the half hearted attempts to bring it back are, to say the least inferior. Yesterday I discovered an actual show stopper: You can no longer adjust the display properly. You used to be able to adjust color levels, contrast, etc. etc. but now, in System Preferences->Displays, you get basically an "idiot box" approach to display adjustment where you can adjust the contrast of your screen and set the native white point, and that's it. Why is this a show stopper? Because not all displays are alike and how they're set up by each user may vary widely. For online image work we used to have about 20 different display profiles to emulate various displays and settings so we could verify that our work is presented in a decent fashion to a user. The ability to do this is now gone. I suspect that any photographer using OS X will find this problem not kind of serious, but an actual show stopper, as in "I can't use this for professional work any longer." As an FYI I was able to overcome this by copying profiles generated in Mavericks onto an El Capitan unit and it looks like it works, but there's no way to adjust anything. In other words, if you do this sort of work, all you need to do is log into a previous release of OS X, generated color profiles, then copy them to an El Capitan partition, then reboot and use El Capitan. This of course begs the question, "Why use El Capitan at all?" The dumbing down of OS X has finally gone too far. I actually can't use this for real work. Combine that with the inability to adjust that bad joke known as translucency to prevent the obvious visual problems it causes some users and I'd have to say the degradation of the OS continues.