My wife and I stayed at Michel's apartment for 3 days and we had such a fun time! This was our first time staying in an AirBnb outside the country. My wife was a little skeptical about the safety but once we reached there we felt very safe both inside the apartment and also where it's located. About the apartment, it was so clean and ready when we got there. The view from the balcony to the Notre Dame was breathtaking. The train stations are close but mostly you can just walk to many popular attractions from this place. The only disadvantage is the - "Stairs". You need to climb a lots of them but we knew this in advance and were prepared for it. So make sure you are in a good condition to climb the stairs. Overall it is a great place to spend your time in Paris!
Tip - We took the train (RER-B) from CDG to St. Michel's station, which is a great way to get to the apartment however we had two huge suitcases and felt out of place. So I would recommend just taking a taxi unless you are traveling light.