My partner and I stayed here for a week in September. It was comfortable and charming for the first few days, but it was ultimately not a great choice for a longer stay. We chose this apartment based on all the glowing reviews, so while I would prefer to only list positive things too, I will share a few details I wish I had known about so future travelers can be better prepared.
Overall, this is a good choice for a short-term stay for one or two travelers on a budget. This ground-floor garden apartment is on a lively public square, so you will feel like you are in the middle of all the action. Locals gather to drink, fight, and sing through the night and well into the morning, so if you have trouble sleeping, bring earplugs. The small shared garden is a nice perk, and if you are only using the apartment for a place to crash at the end of the day, it is charming.
A few reviewers mentioned the comfortable bed...I found it okay, but my partner had two springs sticking into his back and the mattress sloped down on either side. When it rained, the mattress took on a sour smell. Hopefully the host will purchase a new one soon.
The shower has enough hot water for one person to take about a 7-minute shower before it runs out. If there are two of you, decide who will shower in the morning and who at night. There is no barrier between the shower and the floor and the water pressure is strong, so be careful to turn on the water slowly or you will soak the entire room.
If you plan to wash your clothes, run the machine first empty so your clothes do not smell of mold and mildew. We learned this the hard way. Unfortunately there is no drying rack or clothes line in the apartment, so consider packing a long rope or you will live among drying socks, underwear, and t-shirts on every surface!
Finally, if you are traveling in the summer (September still feels like summer in Paris) I strongly advise you to purchase a fan when you arrive. With all the windows open, there was still very little air flow, and between the mosquitoes and the humidity, it was rather stifling. I very rarely (almost never) contact hosts to ask for anything, but after a few sleepless nights, I did ask our host if we might have a fan. She was unable to help us, but agreed it would be a good idea.
In conclusion: if you are traveling for a few days and on a tight budget, the price is reasonable and the location can't be beat. Montmartre is the most beautiful, romantic neighborhood in Paris; you will love it here! Personally, we learned that while we still consider ourselves thrifty adventurers, we need a bit more creature comforts than this flat could provide. I hope this information will help you better decide what's right for you. Happy travels!