We had a wonderful time at Martine & Karim's place! Very easy check-in, great and quick communication, helpful and lovely people. They left treats - bread, fruit, tea/coffee, chocolate - which was a great touch after traveling.
The studio is located in the 13th arrondissement near a metro - you can be in the city/tourist parts in minutes - and during the morning, there are a bunch of markets nearby. There's pretty much everything you need in the studio - only thing is that internet could be spotty at times. Considering I was in the Paris, it was the least of my concerns. I would definitely stay again!