I’m just going to go ahead and link to Jason Snell’s excellent El Cap review for Macworld, as it echoes many of my own thoughts. For designers / developers using a Mac, El Capitan will be a welcome update.
El Capitan (OSX 10.11) is all about refinement, sanding off the rough edges. Considering the breakneck pace Apple has been at with Mavericks and Yosemite, it’s nice to see them tidy up a bit.
I’ve been using El Cap for roughly a week now and I have exactly zero complaints about the new OS. There are so many nice little tweaks and improvements throughout the system that you’ll find yourself discovering new things for a while. The entire system just feels more responsive and snappier, and I fully expect that to continue and increase as more developers switch their GPU intensive apps to Metal.
You should, of course, always make sure all your essential apps have been updated or are compatible before you do an OS X upgrade and backup just in case. Don’t upgrade anything ultra mission critical right away either. Honestly though, once you’ve made sure your workflow is El-Cap Ready, go ahead and upgrade. If you’re already comfortable with Yosemite, there’s a lot to like here and the price is right.