Make sure you bring a print out of the offer if you intend to rely on it - if been turned down on this one on the basis that it only applies to cards issued in India. At DEL anyway, there is not much difference between the lounges (I think the clipper lounge helps you avoid walking up the stairs) but having access to a second lounge is handy as it allows you to perhaps get into a lounge that is only hopelessly overcrowded as opposed to sardine packed.