MO has a great location and the design is outstanding. However, I don't particularly like the bathrooms in the rooms and suites. The one advantage Arts has over the MO is the beautiful views of the Mediterranean from the Club Lounge. The rooms are starting to show their age. If you don't stay on the Club level, there is a wide service drop off and the lobby is way too crowded and touristy. The walk along the beach to the city centre on a nice day is a great.