Depends on who you are. For me the features of a credit card all revolve around convenience and risk minimization. Convenience in that I don't have to fumble around with bills and coins. Risk minimization in that US laws give me far more protection from fraudulent uses of my credit card than fraudulent uses of a debit card (and stolen cash is just gone for good).

Only once have I ever use the deferred payment aspect of a card, and that was a 0% APR offer.