The update includes a number of good improvements including:

The ability to redeem iTunes gift cards in the Mac App Store using the built-in camera on a Mac
Boot Camp support for installing Windows 8 and Macs with a 3 TB hard drive
Various fixes for issues that cause a URL to quit apps unexpectedly, that might cause Logic Pro to become unresponsive and stuttering audio on 2011 iMacs.
The update also includes Safari 6.0.3.