Agreed. I tried the Hill Assist feature for the first time today on several hills on my area. It worked very well. Definitely uses the brakes. Not sure if it just the rear parking brakes or the "regular" brakes. Creaking sound on release seemed to come from the rear so my guess is the parking brakes.
@strider, my wife will also love this feature. Not so important to me, but certainly a convenience.
It's not the parking brakes as they're too slow and you would have heard them engaging/dis-engaging (if you've come to know what that sounds like).