The new Circle Pad Pro for the Nintendo 3DS has pretty darned good battery life. That is a good thing, because removing the battery takes a screw driver to get the plate off to swap the AAA battery. Word is that with one fresh battery you can get about 480+ hours of game play, or 20 days if you were playing it 24 hours a day. Not bad for Nintendo.
The Circle Pro Pad accessory adds an additional thumb stick, or pad, if you will, that makes the 3DS much easier to play for a number of upcoming titles. The big one, of course, is the Resident Evil: Revelations and Monster Hunter, one of two of the big ones that support it.
Word is that we should expect more developers to offer support for it in future releases. That is, of course, if sales of the unit continue at a high enough level that developers keep churning out software for it.