Trickijedi, the interior on EC-GAG didn't look bad at all. The seat fabric was light blue with some type of yellow pattern running through it. I'm sure the interior has been updated several times over the years. The seat pitch wasn't bad, and I got lucky in that people in front of me didn't recline their seats much. It had the older-style movie screens on the bulkhead vs. seatback monitors. The overhead bins were really small, though, which was a drawback. I remember the cavernous bins on my first 747 trip, a United -100 from IAD to SFO in 1997 or so. The interior on that plane, which was at that time probably equally as old as EC-GAG, looked brand new.
Interestingly, on my Europe trip this past June, we got EC-GAG in both directions, so I've actually flown on it twice. From JFK-MAD, it was my wife, my 8-month-old son, and I occupying a window row. From MAD-JFK, we had the same arrangement, but the other 14 members of my immediate family were also on the plane. I was disappointed in getting the plane both ways, instead hoping to get one of Iberia's leased Air Atlanta Icelandic 747-300s so I could add a new type to my list.
By the way, this plane's name is "Calderon de la Barca".