Incredibly conveniently located - literally steps (5 floors of them) from about 100 cafe's, Notre Dame, the RER C, and more. Neighborhood was quiet at night (no problems sleeping), and lively during the day.
The 5 flights of stairs is the only warning I have - if you're not able to walk up and down stairs easily, this place isn't ideal - but if you are, every trip up and down earns you another glass of wine or champagne!