This weekend I updated my seven year old MacBook Pro to OS X 10.11.0 El Capitan.
The issue found initially was that Dropbox would not work, I visited their website and downloaded the latest client and after that things were fine.
So far apart from the usual built in apps, like Safari and Mail I have only tested Adobe Lightroom 2015.1.1. So far no issues. I still have lots of things to test but once I have proved all my key apps and also the screen calibrater, Wacom tablet and Epson printer and scanner work, i’ll risk updating my main work machine the MacPro once OS X 10.11.1 is released.