I've previously flown TATL economy on AA, BA, and Aer Lingus and found the quality of each to be comparable. This past weekend, I flew Iberia for the first time (economy MAD-JFK) and it is, by far, my least-favorite TATL option in Oneworld/IAG. A few of my gripes:

1. When I booked the ticket almost a year ago (AA codeshare - cheap economy fare), they assigned my wife and I the worst seats on the plane (absolute last row). This seems to be Iberia's M.O. based on other posts I've seen on FT.
2. I tried requesting a seat on the website, but Iberia's site didn't cooperate. I tried requesting a seat by calling Iberia, but Iberia's staff didn't cooperate.
3. When checking in on the day of the flight, I asked if we could change our seats. They said alternate seats were available but it would cost 30 euro per person, even though I had Ruby status. I thought Ruby status would have gotten this waived. We declined.
4. There must have been an equipment swap, because our seats were actually not that bad (roughly the middle row of the cabin). I was still seated next to my wife, but it seemed every other party on the plane got separated; some were in adjacent rows and some were multiple rows apart. The kicker was that they made no attempt to re-assign the special meals to the updated seats; it was a free-for-all. After the vegetarian meals were all poached, they brought back fruit and rolls from business class for those who actually reserved vegetarian meals.
5. Speaking of meal selection, I was never given the opportunity to reserve one on their website, as their website was always glitching-out. My wife has a pork allergy and the standard meals were either off-limits for her or risky (options for first meal were: meatballs and lasagna; the only option for second meal was a ham sandwich). I would have requested a pork-free meal for her if Iberia's IT system cooperated.
6. The cabin was hot and sticky. Everyone in the cabin (Americans, at least) were sweating and some serious B.O. issues were going on. When the FA came-through with water, people were clamoring for it. When the FA filled my glass, I mentioned how hot the cabin was and her response was "yes, it is hot". There were no air vents; it was the most uncomfortable flight I've ever taken.
7. Not Iberia's fault exactly, but Madrid's airport is way more stressful than it needs to be. I would prefer connecting in LHR in the future, if given a choice between the two.
8. Relatively minor complaint, but Iberia's IFE selection is poor - Limited selection of movies, and while they offer a decent variety of TV shows, each show only has one episode available.

I already hold a ticket on Iberia for next Summer (AA award in business class) and I might have to change it; I don't know if I want to risk a similar experience again (a lay-flat seat doesn't remedy the above issues). Are Iberia cabins always sweltering hot? Would they keep business class cabin at a cooler temperature than economy?