1. Great location - within a couple minutes walk of three metro stations. If arriving at Gare du Nord, no need to transfer trains. It's a direct trip on metro to Oberkampf. Good cafes and market are all within a few minute walk. Most major tourist spots (excluding Versailles) were within a 20 minute ride of the stations.
2. Property - has all the basic needs: wifi, kitchen, stove top, shower... if you are from North America (I am) then you may not be used to the smaller space but you get a good feel for how the local population lives and in a very non-tourist type area. I was out most of the time anyway so having a good base in which to rest was key. My family was quite comfortable staying in this simple but nicely furnished apartment.
3. Building - this is old school Paris. What you see in the movies is quite realistic. The apartment itself is on the 4th floor. If you are not used to the cardio work, you need to take the elevator up which is super small.
4. Communication - did not meet Gregory but met his friend Rojo who passed over the key and went over all the details of the place. Over the 4 days I was there, communicated with Gregory a few times and he responded in a timely manner.
All in all, I was quite happy with this AirBnB property. Given the opportunity to return to Paris, I would seek out Gregory and his place again.