I went shopping the other day and found that nearly every store I visited offered me a store card. Whilst they advertise the fact that you would save 10% on your shopping none of the stores explained anything more about the card they were offering. Personally I know that store cards are a bad idea because they charge such extortionate interest rates which are often much higher than putting your shopping on an ordinary credit card.
This article talks about store cards and claims that shoppers could actually be paying twice as much for their purchases if they put them on a store card. In some cases consumers could end up paying as much in interest as the original cost of their purchase. The article makes interesting reading but it makes it clear that store cards are a bad idea.