We've been staying for 4 nights with a toddler, the building doesn't benefit having an elevator, but it is manageable to get up and down with a buggy. Moreover the central Paris tube is not suited for low mobility people, there is no elevator and entrance in tube is a challenge with a buggy. The flat is well located with a short walk to the tube, restaurants, supermarket. It gets up to 20 mins to get to central sightseeing by public transport.
It is quite if you sleep in bedroom, if you are on sofa in the living room it may be a bit noisy because of pubs/clubs nearby, but nothing critical. The heating is adjusted automatically to 17.5, we increased it manually to comfortable temperature. There is a smart TV with youtube, etc.
Guillaume was in touch with us all the time, he is very supportive and welcoming.
Overall definitely the great choice for price/value.