My husband & I recently stayed at Margot B&B and had a very pleasant experience.
The location is wonderful! The room overlooked the picturesque Singel canal & it was fun to leave the windows open and just people watch. It is a short walk to the train station, the Anne Frank House as well as Dam Square and the Red Light District.
Margot is very friendly and accommodating. She even helped get the luggage up the steep stairs! Breakfast was always delicious & there were plenty of options to choose from. Sharing a bathroom was never an issue.
If you plan on visiting Amsterdam, I would recommend staying at Margot B&B.