Nicolas' apartment is in a great location.
It's within 10 minutes walk from the old town, even closer to the opera and nearest metro, and with plenty of amenities nearby such as shops, bars and restaurants.
The apartment is in a busy area of town, but as soon as you are inside the apartment - in a very secure building - there is no sound heard from the streets.
The apartment itself is very nice, decorated well and is very modern. Despite hot temperatures outside (30 degrees+) the room stayed quite a good temperature, and even so there is a climate controller which makes the room cooler if necessary.
The beds are clean and very comfortable, as is the sofa bed if a 3rd guest needs it.
Only one small complaint, which would be to add another small sofa or armchair, so that there is comfortable seating for 3-4 people. The sofa is 2 people - 3 at a push - and the other seats aren't the best after a long day of walking! But it didn't affect our stay, we had long days and quickly went to bed.
Would recommend for sure.