We stayed at the Riad during May this year and had a truly wonderful experience. The accomodation was excellent and the staff extremely helpful. Delicious breakfast served on the Roof Terrace, followed by amazing trips exploring Marrakech and the surrounding area - including a very worthwhile visit to the Atlas Mountains. We found all the locals, very friendly and helpful, and at no time did we feel uncomfortable with them.
The only 'discomfort' we experienced was the sight of some English female tourists who were dressed in totally 'inappropriate' clothes for a Muslim City ie bikini tops and skimpy shorts which would have even looked out of place in London. When in Rome etc and a little respects for your hosts culture shouldn't go amiss.