I have used this service more than two times, when I needed to call out in foreign countries. The most recent transaction, in Mexico, was easy and came through within 1/2 a minute. I believe the one in the Philippines took about 1/2 hr or so. In the Dominican Republic, I think I used it, and it worked fine.
In Mexico, the amounts seem random, but they line up with the Paquets Telcel offers.
It's nice to use a credit card and be able to do this from home or a hotel.
Compared to the amounts being put on my funds, the surcharge is a bit high compared to going and paying for credit at 7-11 or wherever.