Whatever else you might say about the much-maligned Nintendo 3DS Circle Pad Pro, you can at least be assured that battery life won't be a problem. The Japanese manual reportedly stakes the estimated life of one AAA battery to last a whopping 480 hours. To put that in perspective, you could play your 3DS for eight hours per day as a full-time job, every day, and still not run out of juice for two months.
Andriasang reports that one fan who just received his pad sent word from the game manual. Sometimes manufacturers overestimate battery life, but even half that amount would likely be reasonable to last most players. It makes sense, as the device only needs to detect the movement of one slide pad and feed it into the system proper.
The flip side of this good news is that removing and inserting a fresh battery involves unscrewing the cover. The long battery life means you won't have to fiddle with a flat-head screwdriver too often, but once you do drain the battery it's going to be a bit more time-consuming to replace than a plastic latch-cover would provide.