TL;DR
Nice boutique hotel, but the lack of overnight staffing of the front desk is a safety concern for this solo traveler.
Overall, this is a nice boutique hotel in a great neighborhood. The rooms are very beautifully appointed (dark and moody if that's your thing) and quite large in my opinion (although take that with a grain of salt as I primarily travel to NYC and Miami), and even come with a kitchenette. The location is superb, just around the corner from Rue Cler. The street that the property is on is very quiet; I'm a very light sleeper, but with the blackout curtains and quiet road, I required neither my earplugs nor my eyemask to get 8+ hours of sleep every night.
My only concern is that the front desk is not staffed overnight (from midnight to 8 or 9 am). As a single woman traveling alone this was of particular concern. There is a disclaimer regarding a "limited-hour front desk" under property details, but I was unaware of this until after my arrival (perhaps this is customary for boutique hotels in Paris or continental Europe in general, but as a frequent traveler in large US cities, I have not previously encountered this). Having known that now, I would not book this property again.