The location is excellent, very practical. Simon's place is clean, well equipped, and comfortable. As is to be expected for Paris, it was a bit of a squeeze for a family of four. Be aware that the apartment is full of Simon's belongings, so you'll have to keep your things in your luggage, and your luggage on the floor. There's an occasional rumble underneath, I'm guessing from a nearby metro line, until 1am and starting again at 6am. I slept through it but it woke up my daughter a little. Otherwise the building and street are moderately quiet.
Overall, a great, clean, practical rental for the price. I think we'll look for a bigger place next time we stay 5 or more days in Paris, but for less than 4 people, or for a shorter stay, Simon's place is ideal.