I have it installed on my Early 2013 15" MacBoo Pro with Retina display, and so far the OS is very solid. Nice new features as well. I have not got to try the new file system or RAID settings out yet. Has anyone dared to take the plunge on a Mac Pro (which I assume most are in production as is mine)? It will be interesting to see if the GTX980Ti is supported out of the box and what else works/doesn't work. I assume the auto unlocking feature using the Apple Watch will probably not work. If I had the extra drives laying around that were disposable, I would install a copy and report. Heck, I may be able to run across a few smaller drives and see how the machine does. I would certainly be interested in any experiences. I'm sorry if this has been brought up in another Mac Pro thread, but I believe it belongs in the Mac Pro forum instead of the Sierra forum due to the Mac Pro users' unique needs.