Upgrade upgrade Mac OS X 10.10 Yosemite when he upgrades Mac OS X 10.9 Mavericks, it can be done directly via the app Store.
The biggest change is the interface, continue to flat, IOS 7 style, the menu font has changed. The two programs you use most and care about are Safari and Terminal.
Safari.app improvement is very large, and finally add Google Chrome a few years ago, "directly in the Address bar search", because never shut down, so the browser will often have N tab page put there, the time is long these tab is not easy to find, single from the top of the tab title can not be fast Quick to identify which Tab,safari menu you want to find on show all tabs can quickly preview all tabs, exactly what I want.
Terminal.app Not much change, there is still no iterm2.app that kind of multiple window segmentation function, can only rely on Tmux to do the window, session segmentation.
Calendar.app is also commonly used in the app, these days can't remember things, rely on calendar/reminder/notes/timer and other tools. Do not know whether the brain degradation and these apps, anyway since you can use a computer after typing, rarely touched the pen, now write out the word of the miserable ~, do not know if we remember the word "calligraphy" ~
Spotlight function greatly enhanced, and the speed of the search is greatly increased, it may be because the hard drive is SSD, the search results can be achieved in real time display.
Notifications added the "Today" tab, users can look at "Today" calendar, reminders, weather, stocks, calculators and other commonly used information, it is said that Apple opened the API, the Third-party program can also display information to "Today", It seems Apple intends to replace the old Dashboard with this new information display page.
ICloud Drive can be opened to System Preferences-> ICloud, 5GB free, and Dropbox usage.
Maybe because my habit is to keep the system minimalist, not using third-party software, no messy software compatibility, interference and other issues, Mac OS X 10.10 Yosemite public beta on my Mac running very stable, can be used as a full version of the ~
After reading this tutorial, you hesitate to upgrade your Mac OS.