I flew this route with Iberia last February.
I was a little worried having read some comments about Iberia crew, but I have to say I had a great time. I think this was helped by the fact that the cabin was nearly empty - but the crew were great.
This was my one and only time in Madrid airport, I did find it massive, and didn't think the lounge was brilliant. But I did like the room where you can go and have a sleep in.
The pre-flight food I didn't think was up to much, and the ambiance in the room was crap.
But everything on board was great, despite a late aircraft change we still got there on time.