As a subscriber you get a new card every day that you do not already have. Otherwise it's pot luck and there's no choice. The cards you get are usually rated in the mid to low range, and if you get cards you don't want then your stuck with them.

Personally I've had about half and half of cards I was very happy with and cards I wouldn't have dreamed of buying otherwise. A few of those I wouldn't have bought turned out to be very good shows though and therefore were a nice surprise. So on the whole I would say I'm reasonably happy with my subscription.