Nectar is very close to becoming a farce, since the cashback element is basically 1%. That really isn't worth the trouble of carrying around a card. In Scotland they are currently trialling a reduced 0.5% Sainsbury's cashback!

However, it saves itself (for me) because
a) I use the points for gym sessions at 500 points a time for Cannons City, one of the UK's most impressive fitness centres, and so the points are worth more than 1p to me;
b) I get points from two Talk Talk contracts that literally turn up with no effort on my part
c) Nectar runs 5-6 100 point surveys a year which take 30 seconds to complete for easy points
d) you get points on Amazon purchases via Nectar E-Stores, and Amazon is not on Quidco, BA E-Store etc