Excellent location! I stayed 3 nights at Nelson's flat and had a wonderful time.
The flat was recently renovated, so everything is very new, clean, and super modern.
The Metro RER 3 Luxemberg or Port royal is a few minutes away( direct lie from CDG Airport ). It is located in a very central place - You can walk to famous sites such as Jardin du Luxemberg, La Sorbbone, Notre-Dame, Centre Pomipidou, Le Marais, Rue Mouffetard, le louvre etc..The host Nelson is a great host and helpfull. He can be reached by Cell anytime during your stay ( although, I didn't have any troubles while I was staying his flat). I really enjoyed my stay at Nelson's place. I'll definitely stay here again on my next trip to Paris! Thank you Nelson!