Apple recently released its latest version of MacOS. Should you upgrade now?
Spotlight: can now pull in information from the Internet too.
Notification Center widgets: can now be produced by 3rd parties.
iCloud Drive: yet another file sharing cloud service but more integrated with Apple's services
Task Sharing: One of Yosemite's main advantages is its ability to share tasks between devices. Continuity and Handoff on the Mac and integration with the iPhone. Not only can you answer and make calls to a linked iPhone, but also easily use the iPhone as a hotspot when you don’t have an available Wi-Fi network
The interface: There will be people who don't like Yosemite’s new “flat” look
The bottom line
So is it worth your while to dive into Yosemite now or not?
Probably not yet. There are still a few issues to iron out especially in performamce of some area, and the new look is atill a bit marmite.
However if you want to give it a go try this method.