The service and staff at the W were all A-one during our short stay.
We stayed in a "fantastic suite" which included a large round bathtub in the middle of the open floor plan. Very chic and sexy room layout. The bed was amongst the most comfortable we have stayed in.
Walking distance to great restaurants and shopping in the polanco neighbourhood, and steps from Chapultepec park, Ideal location.
The only negative I have is the add-on fees for things like wifi, and gym/pool access, for the price of the rooms, these things should be included in your stay.