The apartment is quite well located, it is close to several shops and metro lines and not far from the center. This is probably the only good thing I can say.
We were 4 living in the apartment and it was extremely small, much smaller than what it looks like on the photos. We only had one big luggage that we could fit in the tiny kitchen, but if you come here with 4 people and at least 2 big luggages, I think it would be impossible to put down your luggages and open the sofa bed at the same time.
Other than that, the sofa bed is very uncomfortable, it is not flat and has a hump in the middle which made our nights catastrophic. The other bed was much better, it was spacious and comfortable. As far as the shower concerned, you cannot change the temperature of the water because it is not working, so we took hot showers for the whole time.
The cleanliness of the apartment is acceptable, but far from spotless clean. There were stains remaining on the sofa and on both chairs, I also saw some stains on the sheet (however, that seemed to be washed properly, it was probably a stain that remained anyways). For information, if you plan on cooking something here, bring a sharp knife because there is none that is sharp enough even to properly cut a baguette.
Overall, none of this would have been a huge issue if the apartment cost much less, but for 250 euros per night it is a very bad price-quality ratio (even for Paris).
Note that if only 2 people come to stay here, it is probably a much better experience because you won't need the sofa bed and you'd have enough space for your luggages. However, I would definitely not recommend coming here for 3-4 people, unless you are happy to accept the downsides described above.