The sceptic in me isn't going to buy anything that you need to declare before the point where it comes to pay. If there are genuine coupons that you don't need to declare when reserving or ordering and are just discounts off the final bill then maybe they're worth looking at, but I'm also not too keen on the pre-payment aspect (UnoMas's shut down was completely unheralded, for example - I even had a lunch arranged there with friends for the first day they were closed!)