A quick summary: basically I enjoyed my time at this AirBnB.
In more detail: in the end I gave the property three stars (after some hesitation) because of the absence of curtains (other than thin net curtains) - for someone who's sensitive to light at night like me, this isn't ideal from the point of view of sleep.
However, of course this wouldn't be a problem for everyone, and otherwise there's much to appreciate. The location is very handy - close to the Place de la Bastille (and therefore the Place des Vosges etc.) with its cafés and metro stations but somewhat further up the street from the busiest areas. Handy supermarkets nearby as well. There's a little noise at night, which comes into the studio a bit more clearly because of a small ventilation grill in the window which can't be closed (I think all apartments in the area have them), but it's not a serious issue. Just be aware also of the need to climb stairs to the fourth floor.
All in all, as I say, I had a good time.