Host contacted me by email and SMS. I received the keys and a tour from the helpful building manager.
The apartment could certainly be described as 'cozy'. It was small for 3 people but we adapted okay. Factors which compensated for petite size were as follows:
1. Its location. You can see the Pompidou Centre from the window. It is an easy walk to Hotel de ville, the Seine, Notre Dame etc. There is a good grocery store a few metres away.
2. It is well equipped.
3. The elevator is good fun trying to fit 3 people in at once. (We are weird in that we are not selfies type people but we couldn't resist the temptation to photograph the three of us squeezed into the elevator.)
4. Quiet. We found it to be a lttle refuge from a busy vibrant city.
Overall, it was our first BnB experience and we enjoyed it.
You might enjoy visiting the Carnavalet Museum an easy walk away. It is not as famous as others but it is free, wasn't busy, and was especially interesting re the French Revolution showing models of the Bastille and paintings etc.