Its a spending tool and not savings one. Its for those people who just want to avail credit period of 50 days approx. Follow simple principles, pay the full amount due on the due date, don't go for minimum due amount, and live in peace.
Its in your hand to decide, if you are tempted to go for impulse purchases beyond your repayment capacities then don't blame the Credit Card Companies.
Its a conveniece product for many people but requires judicious usage.