I just stayed here and had a good experience, not great. I booked the lowest-category room on points and got upgraded (as SPG Platinum) to a "sea view" room. It was not bad -- it was at the corner of the property, and had large windows on two sides overlooking the beach -- although I would have preferred a room with a terrace.
I found the concierge service helpful, but the front desk very slow, unfriendly, and with a poor attitude. Prices are high -- EUR 46 for valet parking
-- but I'd expect that, and actually lunch at the sea-side restaurant was moderate (entrees in the EUR 20s) and very good. There's also a great bar at the beach with not-horrible prices (EUR 16 if I remember correctly) for drinks.
The strangest thing was that my room didn't have a shower. It had a bathtub with a hose, but one would have to sit down on the ledge of the tub, or on sort of a seat carved out on the side, to use it. I don't know if they were missing a shower curtain or what, but it was a slight inconvenience. Other than that I enjoyed the room design.
The biggest problem was that they had no record of my reservation. I made it about a week in advance on the SPG web site using points. The night before I arrived, I asked the concierge at the LeM at which I was staying in Paris to call and ask them to add the name of my travel companion to the reservation in case she arrived before me, which was lucky, because the hotel said that they no record of it. About half an hour later and after a call by me to SPG, the SPG desk agreed to fax a copy of the reservation to the hotel in Monaco and the hotel agreed to enter it in the system.
Not surprisingly, when I arrived at the hotel the next day, I had to go through this process again.
They had no record of the call the previous night nor the fax nor did they see anything in their system.
The front-desk agent said that she would call SPG but, no problem, they had rooms available. So, besides another wasted half-hour, it was not that big of a deal, but would have been if they had no rooms. The front desk agents didn't seem particularly apologetic or in a hurry to finish, either.
They attributed the issue to a glitch in communication between systems; who knows what the real issue was, and whether it was the fault of the hotel or SPG. But I hope that I don't have to re-confirm, and then re-re-confirm, every award booking that I make in the future. . .