An anonymous reader writes "John Siracusa at Ars Technica has put together a comprehensive review of Apple's OS X 10.9 Mavericks. This is the first time a major OS X update has been free, and it works on any device that supports Mountain Lion. This suggests Apple is trying to boost adoption rates as high as possible. Siracusa says the following about Apple's move away from skeuomorphic design: 'Mavericks says enough is enough. The leather's gone, the fake pages are gone, the three panes are independently resizable (more or less), even the title bar is bone-stock, and it's boring?' On the other hand, he was a big fan of all the internal optimizations Apple has done, since the energy savings over Mountain Lion are significant. He found a 24% increase in his old MacBook Pro's battery life, and a 30% increase for his new MacBook Air. He also praised the long-needed improvements to multi-monitor support: ' Each attached display is now treated as a separate domain for full-screen windows. Mission Control gestures and keyboard shortcuts will now switch between the desktop and full-screen windows on the display that contains the cursor only, leaving all other displays untouched.' The 24-page review dives deeply into all the other changes in Mavericks, and is worth reading if you're deciding whether or not to upgrade."