Wonderful location, literally right next to Basilique du Sacré-Cœur (at the most 5 minutes of walking). Just keep in mind, Montmarte is a hill, large and steep and stairs are almost everywhere. But if needed, you can get a bus (Montmartrobus) or use a cableway right under the Basilique.
Apartment is located in old historical building just a few meters over the rush and a bit noisy street (logically, Montmartre is just magical), but the whole rented room is reconstructed and it is done beautifully. There is all you need for pleasure stay. It is clean and cozy.
Communication via Airbnb with Maurice was awesome and fast. I fully recommend this stay.