First, the “tenth one free” approach, only works if it’s convenient, people don’t go out of their way for that (in other words, this is strictly for use as a frequent buyer program, or as a customer service reward, in order to pay if forward);

Secondly, speaking as one who, in the past, has only used credit as a source of deferred payment (30 days, & no more), just in order to be rewarded by the creditor’s generous benefit (I’ve always used the Mileage Plus program)… I’ve never used the Discover Card, while I’m sure the cash back sounds good in theory, I’d bet it doesn’t stand the test of time, since the only benefit I can see to a card company from an upstanding citizen, & credit-wise consumer such as myself, whom I’m assuming is your desired market, would be either the occasional lapse (which would negate all value for the consumer), or a downturn in the economy, which would be a double-edged sword, I would presume.

That said, I believe “Discover,” just the word, is a marketing standout; a tool which is easily adjusted to fit a better model, or offering of benefit, to a consumer draw or clout.