The Q-pac booster is only 1000 MAH. The HTC phone battery is 1000MAH.
It takes about 1 hour to add approx 50 charge to the phone. We all know that 50 will not last long.
Stores, namely VERIZON, are charging $59.99 for this very weak booster.
Until it gets much more powerful or cheap enough to carry 2 or 3 boosters its not a good alternative IMO.