The classic apartment with many still intact Soviet and classical fittings is a treasure-trove. I and my wife loved the artistic and thoughtful way in which Marc, Gabriel and Olga have created and maintained the apartment. It is truly an art museum in its league. Marc and Olga were very forthcoming in helping us with some of our requirements.
A note for non-artists: We were accompanied by a bunch of people who had almost no taste for art and they immediately thought of the apartment as queer. If you are not an appreciator of art, if you prefer to visit cheap shopping malls preferable to fine art galleries or museums, if you prefer to search for bottled water in areas such as Suzdal where the water in taps is pure spring water, if you'd rather spend money on sneakers and cheap chinese made clothes than art or true antiques then this apartment may not be for you.
Another note of caution. We were not aware that St Petersburg has a lot of pick pockets. My wallet was picked and I lost a substantial amount of my money and personal papers, thereby almost ruining my trip and the stay in St. Petersburg. Please be advised to be very careful with your money and property in St. Petersburg.
As mentioned, Marc and his crew are awesome people to meet and converse. If for nothing else, the stay at the apartment is worth only to befriend these nice people.