In general, I was not super pleased with the apartment.
First, the good: it's pretty well located in a popular neighbourhood with lots of opportunity for sight-seeing and decent eats. The bed was very comfortable and large enough. Wifi worked well. The fridge was great for bringing home a bottle of white wine to keep cold or some leftovers to eat the following day. The view wasn't particularly special given that Montmartre is on a hill, but it was still appreciated and cute. The curtains were mostly blackout, keeping the house dark when we needed it to be. The lighting was also good.
Unfortunately, that's all that we enjoyed about the apartment. I'm going to leave aside the general look of the apartment because I feel like it's mostly well-represented in the pictures: a little kitsch.
From the moment you open the door, you realized that it was loose and insecure. The apartment itself is very crowded, and small. There is an oversized plant in the dining area, and a large teapot on the cheap dining room "table," which was a foldable $30 IKEA outdoor patio table with spaces between the wooden top. You could not comfortably seat two people. There wasn't much space to put our clothes, let alone our pharmaceuticals.
The washroom was the primary point of friction. The hot water tank ran out when used for ten minutes on what I would consider medium-heat: the two of us could not take out showers one after the other. It was the size of a phone booth and did not have enough space to even take off or put in your contact lenses. You could not sit on the toilet bowl with the door closed without your nose being literally up against the door, and I'm a fairly short person. There was some mold on some of the pipes, which were exposed along with the water tank directly in the washroom itself. The towels did not seem like they had been washed, and the bed did not have a fitted sheet or a mattress cover. The mirror in the bathroom had several centimetres of "rust" on it at the bottom.
All in all we had a great time in Paris but we wish the apartment had been more comfortable.