I have to go along with the other reviews and say that the staff at the El Mansour are just great, always helpful and cheerful. The Riad is nice and quiet, although I really enjoyed the walk through the bustling alleys around it, which gave one a real insight into the lives of the amazingly cheerful locals.
I was a bit disconcerted to find I was the only guest for the first 2 of my 4 nights there, but it was the quiet season. I ate there once and the food was fine, but being the only diner rather detracted from the experience. It was too hot to make much use of the sun terrace and on a couple of days I sought out hotels in the new town which had pools.
I ate mainly around the plaza, as I couldn't see the point in going to Morocco to eat in European restaurants. The food was always good and never cost more than 10 euros.
Marrakesh itself is a little strange, as there is not actually that much to see - the city could be done in 1 day. A trip to the nearby mountains made a pleasant change and the Berber market en route more than interesting, although not for the squeamish as animals are slaughtered in the building next to the meat market and brought straight out - still, I got some good photos of fresh goats' heads! The nights in the plaza are just great fun, seeing the snake charmers, etc, with the accompanying sights and smells all around - I went there every night.
Back to the El Mansour - it's not the height of luxury,but certainly comfortable enough - just lacking tea/coffee making facilities in the bedrooms (where you can't smoke either) and wifi does not work in the bedrooms.