Luvtravlin, we have flown Iberia Airlines a few times, all domestically, that is, within Spain itself. The planes, flights, seats, etc. have been about the same as any other airline. But what has been consistent is this: All the flights we have ever taken have been at least an hour late, EVERY SINGLE TIME! Be prepared to adjust your continuing flights or your land activities accordingly.
But once you get there, Spain is wonderful! You will have a great time there, and see so many beautiful places.