We didn't meet Maurice in person, but the information he gave in advance was very precise and helpful and he answered immediately when there was a question.
The apartment is indeed tiny, but very clean and it has everything you need: a comfortable bed, towels, a fancy high-tech shower and a kitchen where you can cook decent meals. You have to manage the space wisely and rearrange everything sometimes but the studio is definitely big enough for two people.
The location is great and it's really amusing to see the masses of tourists swarming through the alley beneath the window - at night it is, although, very quiet.
There is also a free workout included as you'll have to take several stairs in order to get up/down the hill of Montmartre every time you want to visit a supermarket, laundry, metro etc.