Great location with proximity to both the Marais and Canal Saint-Martin and terrific transit links (even given that the 11 line from Republique was out of service during the dates of our stay). Metro at both Republique and Temple, both steps from the apartment and providing several travel options. (NB, If, like us, you decide to take a taxi back to the airport at the conclusion of your stay, Place de la Republique has a taxi stand on the south side of the square, near the No. 2 entrance.)
Apartment is smart and well decorated as shown in the Airbnb listing. Very convenient to have not only 2 bedrooms and 2 bathrooms, but a full kitchen (with dishwasher, full-sized refrigerator, and oven/range - NB, no microwave) and washer and dryer. The only drawbacks I see about the space are these: (a) because it's just under the roof, it was at times uncomfortably warm (though the host provided a small fan which would easily be carried between the upstairs and downstairs as desired), and (b) there didn't seem to be places to store our clothes (and even surfaces were at a minimum, so we did a lot of piling of clothes onto chairs). Also, because of the unique space just beneath the roof, taller guests might feel a touch claustrophobic in the upstairs, where the ceilings are angled.
All in all, though, we had a great stay and definitely recommend Karim and his apartment to future guests.