We stayed in Krystell's place for 3 nights and we highly recommend it. We are a party of four (parents with two teenage daughters) and the space is small but with beds for two couples. A bit tight but workable for four and perfect for two.
The most important feature is the location 100 meters from the side entererece to the beautiful park surrounding Sacre Coeur in Monmartre. The lovely bars and restaurants are litterally downstairs.
You cannot find a better value for money then this.