Samy's apartment was really amazing. It's an old building so expect wood stairs and squeaky floor. Really well organized and cozy. We never met Samy but his neighbor Nadia showed us the apartment ad commodities. Samy's place is really near various metro stations like Jules Joffrin on the 12 green line and Simplon and Porte de Clignancourt on the 4 purple line. The Sacre Coeur is at 10min max by walk so you're basically in the center of Montmartre. Really an amazing stay, totally recommended. Samy is a great host and he's always reachable by text or phone calls.