Fast Browsing. New WB Adjustment. New H/S Recovery, and Professional Auto Enhance:
It uses powerful image analysis to determine the correct white balance, exposure, vibrancy, curves, highlights, and shadows. And it intelligently applies these adjustments to your photos. So when you’re refining images, Professional Auto Enhance is a great starting point. Then you can tweak images further until they’re exactly the way you want. Or you can give photos a professional-quality pop — with just a click.
Oh, and there’s the unified iPhoto-compatible library format, which I presume — including the above new features — were taken straight from Aperture 4.0.