There were a few problems with early production where the battery compartment leaked (it's separated from the rest of the electronics). As you can imagine, water decreases the battery life quite a bit.
And out of thousands sold, a very few have ended up with batteries that didn't last as well as they should- Atomic has replaced them. But batteries not lasting is not a complaint we have had. You will get 40 to 60 hours of actual diving time or six months of standby time out of a fully charged battery, and the batteries themselves (typical Lithium Ion) should last 500-700 charge/ discharge cycles before gradually losing capacity. The battery is easily replaced by a dealer (where you need to go to get it anyway), but for most users the battery will never need replacing. It takes about two hours to charge fully from the wall charger, and about four hours from USB.