Ars Technica has a fantastically detailed review (25 pages) of the latest OS X release, Yosemite. I’m browsing though the article as my 5.1GB download is slowly coming across the tubes. Maybe sometime tonight it will have completed and I’ll be ready to install 
In the meantime, I’m wondering whether I like the ‘flat’ UI look, and prefer the 3d style icons and shadows in my dock, but I’m sure I’ll get used to it.