Max ISO finally! That alone is HUGE for me. I shoot a lot of concerts, and the auto ISO constantly varies between 400 and 3200. Never been able to find the "right" manual ISO setting, since lighting conditions change so quickly and so drastically, so always had to use auto. Some shots at 3200 are useable, but being able to cap it at 1600 or so will be a huge, huge help.
Audio... I guess that's helpful, but any video I'd be doing that I wanted to look and sound "professional" I'd have an external audio setup anyway.