I bought this kit in a pinch a while ago at Best Buy and had to use a coupon before it expired. I knew I was taking a gamble on quality with a first-run accessory that came out so soon after the system itself did.
The battery is nothing to rave about, it's a battery, it has fashionable zig-zag lines to tell it apart from other batteries, I guess--and it didn't start losing full capacity for the first few months. By month 5 or 6 of moderate-to-heavy use (5-10 hours a day, at least 4 days a week), it seemed to go from needing to be charged every two weeks, to every 7-9 days or so. Not a deal breaker, the 360's battery paks saw a degradation in their charge in less time.
I loved the cord, however. Extremely generous length, snazzy bright green ends, and an ingenious light that went from orange to white when fully charged. Unfortunately, the cable started failing me after about three months in. I started noticing something wasn't right when I'd leave the controller plugged in (with a USB wall-plug converter, sold separately) for an hour or so, come back and turn it back on to play and I'd get the familiar pop-up telling me my controller was dead, still.
Sure enough, something must've came loose on the inside of the cable, if I wiggled the end while it was plugged into the controller, the light would go from white (fully charged) to orange (charging) to non-existent. And the longer I tried using the cable, the looser that range became. I'm not rough on my cables, not like some people; I don't smoke, I don't kink them, I don't have a dog or a toddler chewing and trampling my cables. I feared that I bent the port on the controller itself, but nope, that still works fine with any other cable.
So here I am, about a year later, and all I have to show for my purchase is a half-chargeable battery pak that I plug in with any ol' micro-USB cable that's floating around, and the memories of what was.