The good: Host gave us a bottle of wine! Very clean, and the neighborhood felt safe even later at night. Near 2 different Metro stations! Close to Montmartre.
The bad: Extremely tiny and not much room to do anything except sleep. If you are claustrophobic, this is not the place for you. Be prepared for ample street noise which may make sleeping difficult for light sleepers. (Host provided us a fan, which greatly helped create white noise to block street sounds.) Must be very conscious of your own noise levels.
The verdict: Great bargain, helpful host, and a clean/safe place to sleep. Can't ask for more for the price!