The battery is proprietary and the battery life has always been dismal. You need to buy at least one spare and always carry a spare. They die rather suddenly. I make sure I have at least one fully charged spare before I take the camera out. I charge the one I used that day whether or not it's low because I know it won't make it through a second day. You can buy generic replacements on eBay and elsewhere for a lot less then the Pentax branded batteries.

I have never dived with it. It has been dropped once in knee-deep salt water while exiting the dinghy and exposed to spray many times with no problems. I wouldn't take it deeper than about 3 feet, even though it says 3 meters.

Picture quality is OK -- but there are better lenses on cameras that aren't so tightly sealed. Sample (compressed for web) image below.