engadget review on Nyko Power Grip for Vita: http://www.engadget.com/2012/08/16/nyko-power-grip-for-playstation-vita-review/
I hadn't realized this was already released a while ago. I was interested in it when they first announced it but it looks like they scrapped their prototype from before.
Pros: Doubles the battery life, grips look really comfortable, $25
Cons: Blocks the game card slot, pretty bulky, rear touchpad is more difficult to reach.
A word on battery life from engadget:
"The company claims the device doubles the Vita's battery life, and we found that it did just that, offering twice as much longevity or more. Set to maximum screen brightness and volume settings, the Vita's standard three-hour runtime jumped to more than six. The four hours a dimmed-down and muted handheld can achieve doubled as well, dragging on for nearly eight and a half hours under the Power Grip's wing. Shifting into PSP mode prolongs the battery life even more, topping out at 11 hours at medium brightness -- more than enough to keep one occupied on a trip across the pond."
I might get it. More battery life is very appealing and 11 hours if you're playing PSP games? Awesome. If I want to take it off to switch games or to have easier access to the rear touch, it doesn't look like that'll be much of a problem. The part on the grip that connects to the charging port can slide and lock into place. You can also charge the Vita with the grip installed.
