Théo's apartment is wonderful! He recently renovated, and the place was spotless.
Check in and check out were both flawless. We were coming from another European city via train and he was very flexible about the check in times.
The apartment is a short walk from all of the major attractions (Louvre, Muse D'Orsay, L'Orangerie, Notre Dame, the Pompadou) and is easily accessible by public transit from both airports and Gare du Nord.
The neighborhood is one of my personal favorites in all of Paris. There is excellent shopping, art galleries, comic book and hobby shops, and restaurants/cafes all within a quick walk. Le Marais, another great place to walk around for an afternoon (or week) is also a quick walk.
Théo is a fantastic host. We had the pleasure of meeting him one evening and he was extremely welcoming and helpful.
I would definitely recommend his apartment to friends and family, and cannot speak highly enough of both Théo and his apartment.