We had a fantastic stay in Paris for our anniversary at Agnes' flat in Montmartre. The view from the balcony across the square and down towards the city was a highlight and we were able to enjoy dinner in the late summer sun one evening.
It was great to be welcomed promptly on our arrival with good communication from the host during our journey and they were flexible about our departure time on the final day, which saved us carrying our luggage all day!
The noise from the cafe below was a bit of an issue on the first night, but i suppose you have to expect it staying in such a busy area and we slept fine on the other nights. It was also particularly hot weather which was great generally but meant we had to have the windows open at night.
We would definitely recommend this flat for a couple looking for a base to explore Montmartre and the rest of Paris.