The new beta, build 14D87h, is available for registered developers through the Software Update mechanism in the Mac App Store and through the Mac Dev Center.
OS X 10.10.3 brings several new features to Yosemite, including the new Photos for OS X app. Photos is designed to serve as a replacement for both iPhoto and Aperture, and is on track to see an early 2015 launch. Early reviews have suggested that while Photos is a suitable replacement for iPhoto, with more advanced tools and performance optimizations, it may leave professional users disappointed, at least in its initial incarnation.
The first beta of OS X 10.10.3 also brought a new emoji picker that consolidates emoji into a single page with clear labels, and support for Google 2-step verification when setting up accounts in System Preferences.
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