This update introduces a new iTunes widget for Notification Center in OS X Yosemite. See what’s playing, skip ahead, and even buy songs while listening to iTunes Radio — right from Notification Center. This update also improves performance when syncing with your iPhone, iPad, or iPod touch.
iTunes is now a full 64-bit application on 64-bit editions of Windows 8, 7, and Vista. This update also includes bug fixes and improves performance when syncing with your iPhone, iPad, or iPod
For more information, please see: http://support.apple.com/kb/HT6546