There is such a large choice of restaurants and bars in Nidri that you will be spoiled for choice. However always remember that 'one man's meat is another man's poison'. Also, every restaurant in the world has days when things go wrong. A waiter, or even the chef, may be missing one evening. Or a piece of meat may have been delivered that is unusually not up to standard.
Sometimes the prices on the menu may seem a little expensive, at least by Greek standards. However, if you are eating at a good, Greek taverna you will find that the courses are often large enough for two people. For example, a Greek salad as a starter is always enough for two people. Order individual portions for the centre of the table instead of a set meal. A portion of chips, half a kilo of lamb chops should work out cheaper than a meal each. If you have started with a salad there is no real reason to order vegetables, unless something takes your fancy.
For parties of four or more you can really have fun. We always choose two starters between four, and a tsatziki for the bread,useful while you're waiting. Look for a 'platter for two', it is often enough for three. If you really want to experiment ask the waiter for a 'meze', a mixture of starters that would be enough for a complete lunch.
As eating out in Greece is a social occasion good conversation is more important than speedy service, and you're on holiday so what's the rush? Personally though, if I hadn't been served with a drink and some bread very soon after arriving I would leave.
Talking of drink, please try the local wine. Order it by a a half or full carafe. The island's red wine is particularly good and a lot cheaper than buying a bottle.