We were upgraded to J on ORD-MAD last week, and everything was just fine except the main course was inedible.

Of course we have the same problem with food often in Spain, because apparently salt is heavily subsidized there so they use it in place of other ingredients. The next-most-used ingredient in Spain is pork fat.

The J seat is quite comfortable, but (unlike BA's window seats) there is no privacy, you are sleeping right next to another passenger.

We came back in the class we paid for (coach) and there was nothing particularly good or bad with that flight. Everything perfectly normal.

The food complaint seems reasonable, as I have flown next to many non-europeans who are not too fond of any of the choice of 3 main course offerings, are surprised to not find the usual US carrier standby¨steak and potato¨ like offering, being as Iberia follows an entire Spanish cuisine regimen when preparing the menus.
One great way to combat this is just to order a special meal, usually they can even tell you over the phone what such and such special meal will consist of, and you don't even have to worry about it.
However, if you are a fan of Spanish/Mediteranean cuisine, the Iberia meals are usually very good for airline food and the wines especially are all top-shelf offerings.

As someone who flys heavily between MAD and the US and vice versa, I still think the J seat and service they offer is the best in the US-MAD market.