Apple’s Mac platform has had a great year. At a time when traditional PC consumption is shrinking, more people are diving into OS X, and the next big upgrade is Yosemite 10.10. Revamping the interface, eroding the barriers between iPhone, iPad, and your MacBook, and seamlessly connecting local apps and the cloud, Yosemite promises to be not only an ambitious upgrade, but a capable one. Now, on the eve of the new OS X Yosemite Beta Program, we’ve been putting the latest release through its paces. Read on for our full preview.