Are there any strings attached to "nectar cards"?

It depends on what you think of as strings. the benefit of a nectar card for the controller is being able to gain market research on what you buy in stores such as sainsbury's, thus giving them a good idea of what you like to buy and sending you offers which appeal to you and make them more money. If this dosent annoy you then , no. It's big brother again, isnt it?