I bought this charger around December and so far this is what I can tell you about it.
1. There's no way to tell how charged te batteries are using the xbox button in the middle of the xbox controller, when you do the bars for the battery life are always full so you wont know when the charge is going to run out.
2. The charging stand where you put the batteries on isn't designed very well for charging the batteries without them being attached to the controller, if you try and charge them without it connected to the controller you have to try and line it up just right with the little LED on the charging dock and the battery, if you don't the light showing you how charged the battery is will stay red (no/low battery power) and will never change to yellow or green (fully/high battery power), resulting in you over charging the battery. The easiest way to prevent that is to just have the battery connected to an xbox 360 controller when you charge it and it will slide right into place. (P.S. I myself might have accidentally over charged the batteries because the light indicator showing how charged the battery is will only go to yellow. I'm not sure if this was caused by me or if the batteries themselves were defective or something of that nature.)
3. The average time the batteries last after being charged is around 3 to 5 hours of use, which is abit shorter than other batteries but if you aren't using both of them and have a second xbox 360 controller (you can charge the batteries without them being attached to the controller, it's just harder to line them up with the charging bay!) you can pop the dead battery into there and put that on the charging bay and then rotate them when those batteries get dead. If you are using both of the battery packs at the same time however get ready for some downtime for you and your friend for the batteries to recharge.
4. The instructions that come with the "Xbox 360 Power Base Induction Charger" do not tell you how long you should charge the batteries for or how long you shouldn't charge the batteries for in case the light indicator is messed up or something. (As stated above my batteries no longer show a green light when charging and will only show a yellow one.)
1. The batteries work, I've had them for a few months now and they still stay charged for 3-5 hours of use.
2. You can use rumble without the the xbox 360 controller turning off (I'm talking about the issue for the xbox 360 controller where when you use rumble the batteries jiggle out of place for a moment and then that turns off your xbox controller which can get really annoying for online play or playing in general. Here's a video showing you a fix for that problem in case you decide not to buy these. [...])
3. They are really light making the xbox 360 controller alot lighter (Not sure if everyone sees that as a pro, but I do.)
4. The charging dock is small and lets you charge two batteries at once and they don't have to be connected to the controller to charge (but it is harder to charge them without being connected to a controller.
I would also like to add that I do not know if the batteries automatically stop charging the batteries once the charge light turns green to prevent over charging the battery, but I it might. If anyone knows a added comment to confirm would be great.