We had the luxury hamman and stayed for the evening meal.
Overall I would say the Spa was above average. Service was excellent and the inside of the Spa itself is amazing to behold. They really did a great job redecorating / renovating (read the history of the place in the book while waiting).
The dinner on the other hand was not good. Drinks and canapés were nice, up on top of the beautiful terrace bar. They came and took out dinner choices and we were settling in for a beautiful evening watching the sun set over Marrakesh, then confusingly we get moved downstairs to the back of the reception / spa in the dinning area. It just didn't make sense. The food itself was trying way to hard and even stranger had only the remotest connections to Moroccan cuisine. It didn't really help that I was violently ill the following day and missed most of the last day in Marrakesh....I can't say for definite this was from the fish I had but my partner had the lamb and was fine, having eaten exactly the same as me all day except that meal.
Overall the spa is above average but let down by food that is trying way to hard (I had a meal 5 times better in the central square at a stall for less the 10% of the price 2 nights earlier) and slightly overpriced. Worth a visit for the spa though. I would have give the Spa a very good (although just about).