Reviews, overviews, tips:
- If really long and detailed reviews are your thing, John Siracusa has you covered with his Yosemite review - in various formats.
- For a quick overview of Yosemite, check out David Pogue's video review.
- Federico Viticci posted a nice collection of tips, tricks, and details on MacStories.
There are of course many more excellent posts, but the above is a nice sampling (and I try to keep things short).
- I don't need to tell you to back up before updating, right?
- Apple's page on how to upgrade (including hardware requirements and feature requirements)
- How to make a bootable OS X 10.10 Yosemite installer drive
- A possible fix in case some documents don't sync properly with iCloud Drive.