Apple gave a few outlets advance access to macOS Sierra. Jason Snell's take is my favorite:
The X is dead—long live macOS. With this fall’s release of macOS Sierra, Apple is bringing some familiar iOS features to the Mac, along with interesting interactions with iOS hardware, a dramatic expansion of iCloud, a major update to Photos, and a lot more. I’ve spent the past few days using an early beta, and here are some first thoughts about where Apple is taking the Mac in 2016.