Overall, I was very happy with my stay in Alain's apartment. Omar, his friend, met us on arrival and he was sure to tell us everything we needed to know about the place... He showed us how all of the appliances worked which was much appreciated.
The apartment itself is very small. There is a pull out bed as well as a single bed so I had my brother staying with me as well which made for a very cramped space but this didn't matter as we were only there to sleep - for one person though, it is a perfect size.
I wish there had been a microwave though... It's something I think it misses. Also, there's no lift to the apartment which is on the fourth floor - that didn't bother me but some people mightn't like that.
The apartment itself was located just behind le Moulin Rouge, literally 5 min walk to the metro. Only 15 mins from le Sacre Coeur and if you plan on buying a Paris Pass, it's about a 20 min walk from where you need to collect that. The area is safe, though very touristic and there are lots of lovely cafes and bakerys on the street. Good tip as well - if you are looking to buy some cheap groceries - Monoprix is just down the road from it and they were very reasonable!!
It was very quiet and we got good nights sleep except on the last night, our neighbours seemed to be having a party because there was loud music playing... But I was so tired after all the stairs, that I conked out immediately!! ;)
Would highly recommend this apartment. Wonderfully located and very reasonably priced.