We spent a month at Isabelle and it felt like we truly lived in Paris! Her apartment is located ~5-10 minutes walk from the most charming parts of Montmartre (Sacre-Coeur, La Maison Rose). It is a very short distance to the metro which makes it accessible to all the major monuments and major train station.
The apartment itself is beautiful with wooden floors and moldings and is typical parisian! It has 2 adjoining bedrooms which is great f you are traveling with kids (but less ideal for couples/friends). Her decor is eclectic, bohemian and even 'spooky'! One drawback is that there is no central air conditioning but Isabelle provided a small fan for the bedroom which made our summer stay tolerable.
The neighborhood is lively (although you don't really hear any noise while in the apartment) with plenty of bars, bodegas and restaurants if you need a quick bite!