#14 Simplified contacts manager:

It’s true that Apple had to face a lot of criticisms for their awkward looking contacts manager, which was incorporated in their previous versions. But now Apple has decided that a change is inevitable and has brought forth the former in a newly released OS X Mountain Lion. The contacts bar is better managed using sliders and well arranged panes, which is also integrated with social networking services. The OS has its contacts service integrated with Facebook, Twitter and also with Apple’s Messages chat app.

#15 App preview clustering control:

App preview is one of those features that users often get confused with. What it does is that it collects the entire app and lets the user see all the open windows and apps in his present desktop. In OS X Mountain Lion, Apple has introduced a Mission Control enhancement where the windows can be arranged and can be presented individual of each other.