We loved this place; we stayed for a week and found it well located, great area. Laurent was accessible and really helpful with information before we arrived; arriving was hassle-free and easy. We're keen walkers and we found the apartment to be easy walking distance (about 20 minutes, with bags) from Gare du Nord, and walkable to everywhere else in the city. Having said this, super close to buses and Metro stations as well, really easy to get around.
As noted in other reviews- plenty of stairs up to the apartment, but it helps to justify all the amazing food Paris offers, and you're certainly fitter at the end of your stay!
The apartment is well sized; a spacious bathroom, space to tuck bags away, a lounge great for relaxing with cheese and wine in, and a quiet courtyard to look over. A few supermarkets within a few minutes walk and a well-equipped kitchen to use if you'd rather eat in. You can relax and feel like a proper local when you're not out touristing, and still be happy tourist-distance from wherever you need. We'd happily stay here again, and hopefully will be able to soon.