So far the sound hasnt been great, but i think thats down to where i've mounted it on my bike as there's a lot of wind noise, which sounds stranger when its in the waterproof case.
I've yet to try it out of the case, or with an external mic.
I know the battery outlasts the 8GB card i'm using atm, which gives about 1hr 20 on full HD. But the batteries are external so I plan on getting a spare at some point.