Stayed here for nine nights. Used SNA to upgrade to an executive suite and then further paid upgrade to their Premier Suite.I believe the suite is one of the best I have been in London. However, as mentioned above, the service is not in-line with the Hard product of the hotel.
We've had problems on a daily matter, from forgetting making the sofa-bed and closing it on a daily basis, refreshing the wine glasses and leaving the used ones in the room. Notifying that the mini-bar is free of charge for non-alcoholic items but then being charged for it after check-out.
Lounge was OK and nothing to cry home about. Grosvenor House and Grosvenor Square are much better IMO.
Point haven't posted yet even though I have checked out 9 days ago, so it seems I will submit a missing stay request.
All in all, 830 GBP per night for the premier suite sounds like a steal, but the service level you can find it at any lower level Marriott Hotel. Where the hard product is of a Luxury collection property.