Location location location! This place is central to absolutely everything! You can walk to The Louvre, Palais Garnier, and a ton of other stuff. You MUST eat at Chartier at least once (get the duck, and use as much French as possible to make the waiters like you).
The one drawback of this place is that it's directly above a comedy club, and that place is really noisy until midnight. If you've got a light sleeper, that can be a challenge. If you intend to be out late at night, then it's no issue at all.
Patricia is lovely and helpful, and ready to answer whatever questions you might have.
Also, seriously, eat at Chartier. We ate here at Patricia's recommendation, and it was fantastic.