This is a great apartment for a long term stay in Paris. We rented it for 30 days. The location couldn't be better. It is close to Pont Neuf, Il de Cite, the Louvre, the Metro, the RER, and many outdoor cafes. We loved our time at 20 Rue Dauphine.
Rue Dauphine is a lively street. There are several bars 4 floors down that can be very busy at night. My husband and I live in Baltimore City, so we are used to urban noise. We actually loved the hub bub on Rue Dauphine. So it's not a quiet street. We slept in the back bedroom and that room was peacefully quiet. We found the bed very comfortable.
This apartment has beautiful floor to ceiling windows and some nice paintings. There is a great breeze when the bedroom and living room windows are open.
Keep in mind it is a 4th floor walk-up (ou le troisieme etage). There is a beautiful winding staircase and 65 steps brings you up to the apartment. For us it was great exercise.
I truly recommend this Paris apartment. I wish I owned it!