We ate at Riad Kniza on our last night in Marrakech. The meal was the most expensive we had but the food was up there with the best.
The service in the restaurant was impeccable, couldn't have asked for anything more. Make sure you go with an appetite as there is plenty to eat!
The food itself was very good. I couldn't pick out an individual element which was better than the same dish I'd had here or there in Marrakech but the overall package was certainly by far the best in terms of consistency.