I updated to Sierra today. One odd thing: The download was for 10.12. After installation was complete, I saw that 10.12.1 was available. I had thought that the latest version would automatically be installed (this has happened in the past).
Otherwise, everything went smoothly and, so far, all seems well. I had to update Glimmer Blocker, Cocktail, OnyX, TinkerTool and TinkerTool System to their respective Sierra versions.