Marianne's apartment is very well positioned for anyone who would like to do most of the sightseeing on foot like we did. The place is small but cozy (the bathroom is a bit moldy). For the three of us (adults), it was more than enough especially since we were out most of the time.
The stairway is a bit narrow for persons with luggage and since the building is surrounded by restaurants it can be a bit noisy early in the morning during the garbage collection (glass from the restaurants).
All in all most of our spots of interest were within walking distance and we did spend three great days in Stockholm.