Here are some posts worth reading, each with an individual take after spending some quality time with the macOS Sierra beta.
Dieter Bohn for The Verge: macOS Sierra preview: Siri is just the beginning
Rene Ritchie for iMore: macOS Sierra preview: Smarter, easier, better
Jason Snell for Six Colors: Hands on with macOS Sierra
Jonny Evans for Computerworld: First look: A week with macOS Sierra
Andrew Cunningham for Ars Technica: The macOS Sierra developer preview: Different name, same ol’ Mac
And, of course, there’s Jim’s walkthrough.