This was the perfect spot for us for our week in Montmartre! The studio is clean, modern, safe, and conveniently located just steps from the Place du Tertre and Sacré-Coeur basilica. On the 1st floor (2nd floor if you're an American) you are very close to the cafes and shops outside, but it still feels private. The sofa-bed is comfortable and we slept quite well; the apartment also stays cool even on hot days if you open the windows a little bit. (Though the trash pickup in the morning can be noisy -- it did not bother us at all but you are very aware of the world outside the apartment if the windows are open!) We were very happy during our stay, and highly recommend Soline's place.
A final note: If you're coming from the south, be prepared to carry your bags up many steps -- the Lamarck - Caulaincourt station is a much easier walk.