Overall the interaction was very good and for each question I had Battery Upgrade answered back promptly. The bad part was the time between the order and the delivery - almost 1 month.
About the product:
I ordered a bigger battery for my HTC Sensation. The one that comes with the phone has 1520 mAh and it is just not enough for the phone. The new battery is a little bigger - 1700 mAh but can tell the difference.