The location is perfect, right in the centre of Gamla Stan and with a lot of restaurants, bars and the royal palace right around the corner!
The apartment is lovely and has a lot of amenities provided by the host.
Check-In is easy, as everything is locked via Keypad.
Nevertheless if you come by car, i recommend the P-Hus Gallerian. Its around 350 SEK for 24h(a lot cheaper then in Riddarholmen) and very near!