I tried a credit card once at the Keisei counter at NRT and they wouldn't take it. Wasn't buying the "deal" though, just a regular ticket to Tokyo.

Note that a 2 day metro card can be bought at NRT for Y990, the Keisei deal saves Y500 over separate purchase. I expect that this metro card is not good on the 4 TOEI metro lines, like the separate card.