The place was great; like other people noted, the photos do not do the view justice - it is even better in person! When you are not roaming around Paris, you will want to sit back on the balcony and stare at the view. The apartment is exactly as described in the profile and is perfect for what you need. Waking up to the view alone, will kickstart your day! The apartment is in a perfect location, situated on a great street with a delicious bakery just steps away as well as a grocery store literally next door! The Metro and transit access for the airport and getting into town is easy. I would say though, do not catch a cab to the apartment from the Gare du Nord station - traffic is a nightmare there and it is a lot easier to walk or take the 42 bus.
Sebastien is a great host; he met us at the apartment for our arrival, "walked us through it" and then spent an hour or so chatting and giving us great tips on our visit to Paris. He was also easy to reach for any questions or issues during our stay.
If his place is ever available on return visits to Paris, it will be our first choice for sure!
Tips for your stay - stock the fridge with Champagne and wine so you can enjoy the view and living "Parisian" life :)
If you are staying for a few days, look at getting a weekly pass (21.25 Euros + 5 Euros deposit for the card + 5 Euros for photo) as it is 10 Euros from the airport to Gare du Nord alone and 1.80 from the train station to the apartment. If you use it to travel around, this is by far the best cost savings - instead of a 5 day pass (for example). A weekly pass is valid for Monday to Sunday only - zones 1 - 5. You can use this same pass to go to Versaille.
Across the street is a cafe called Odette & Aime - the salads are delicious and huge!
Staying at Sebatiens, you can live like a local so enjoy all it has to offer and enjoy Paris!