For Game Card itself, I can say that I have paid via Game Card for 3 years WoW games, and from the very beginning. The advantage is that you can tell by the 2 months, I do NEN month break. If you pay for example for half a year (if it can xD) then you as a player more or less forced to play, so you do not pay for nothing.
The shipping and Support of Amazon is as always super fast and easy. Game Card purchases during the holidays Monday at 10 clock in the morning and on Tuesday it was already there (without Overnight Express).
Therefore, 5 stars from me ...