Just like clock work, every year Apple releases major updates to their operating system. And accompanied by every release is John Siracusa's comprehensive review posted on Ars Technica. You can always read it for free on the website or do it like me and buy the complete ebook.
I've come to love his thoroughness and learn quite a bit when reading it on my Kindle or iPad. Available now for only $4.99, sit back and enjoy the tour of Apple's latest Mac OS X 10.10 Yosemite. Make sure to grab a Field Notebook and your favorite pen to jot some notes.
While you're at it, be sure to also check out Austin Mann's review of what Yosemite and iOS 8.1 offers photographers in his "Need To Know".