Oilve oils take on different qualities from the different lands they are produced:Italy, Spain, Tunisia, Morocco, France, Israel, Greece, etc. They say you should use olive oils nearest to the kind of cuisine you are preparing -- Spanish olive oils for maing tapas, Israeli olive oil for hummus, French olive oil for vinaigrettes, and so on.
I don't cook with anything else, as a matter of fact. It is true that olive oils differ according to region--I recently went to a shop that only sold olive oil products and learned a lot about the subtle differences. Not only is it great with food, but of course, it's wonderful for the skin and when it's in shampoos and conditioners.