Mavericks continues Apple's recent trend of launching more regular low-cost updates to OS X without any major changes but which add some new features and improve integration with iOS. Although it doesn't introduce any revolutionary changes to OS X, it includes some nice features, especially for fans of iOS, Maps and iBooks. OS X 10.9 Mavericks supersedes OS X 10.8 Mountain Lion and is the first version of OS X to be free.
Softonic review The new version of OS X for Mac