My partner and I spent one month at Stéphane's lovely little apartment in Montmartre. It is a sunny loft style with a small kitchenette and a separate bedroom with a curtain door - a small but adequate size for a couple.
The bathroom is very tiny which was as expected so not a problem - we just got used to ducking our heads and having quickish showers!
The kitchenette has a fridge and two cooktops, a few pots, pans, cutlery etc. We cooked a lot during our stay and the set up was fine. Having a clothes washer/dryer is also great.
The apartment is on the 6th floor of a typical old Parisian apartment building with no lift. Being high up like this in Paris is ideal though, as you have minimal street noise despite your location, a beautiful view and usable balcony's. Stéphane was an excellent host, quick to respond when we had questions and very friendly when checking in. The location is great - you are literally a stones throw from the Sacre Coeur chapel and tourist shops, Rue des Martyrs for market-style food shopping, and Pain Pain which has (we think) the best patisseries and baguettes in Paris.
We found it very easy to walk down to the Seine and central arrondissements each day, museums etc, and did not end up using public transport at all. We were able to walk to the apartment from Gare du Nord when we first arrived and when we left too, which was really helpful.
Overall we had a great stay at Stéphane’s place - we'd definitely recommend it!