Ok firstly i bought this when i started to run out of AA batteries, for those that don't know the XBox 360 wireless controller EATS AA Batteries for breakfast so i recommend you invest in a recharge kit which also doubles as a plug and play kit. The battery pack fits nicely into the controller and doesn't rattle, the cable is more than long enough and also fits nicely into the controller(the cable plugs into the USB port on your console). NOTE: this black version will work with the white controller.
PROS: no more batteries, recharge and play at the same time, long cable for recharging, fits well into the controller
CONS: Pack does not last as long as batteries but is quickly recharged, XBOX needs to be switched on to recharge the battery, battery can get hot while charging.
VERDICT: despite it not lasting as long as two Duracell batteries on a full charge, its cheaper and you'll save yourself a fortune on batteries in the long run, it's well made and works with all 360 controllers, (one word of advise is to remove the battery from the controller while it's not in use as this does help prolong the charge in the battery!)
RECOMMENDED for those who play 4+ hours a day