We had a wonderful stay at Jean-Marc's apartment. The communication with Jean-Marc went flawless and our arrival and departure was a breeze. The location is good: next to a metro/underground-station (<1 minute walk), supermarkets are close-by and it's close to the wonderful sights Montmartre has to offer. The apartment itself is small, but I consider that a positive thing since it guides you to go out and explore Paris! Also, while being small it features all the comforts (for example an easy to use kitchen and shower) to give you a pleasant stay. I recommend this appartment, but take into account that it's on the 5th floor of the building so it requires you to be able to climb a lot of stairs.
In conclusion, we had a wonderful stay, clear communication, good location and an apartment with all the welcome comforts. Merci, Jean-Marc!