My wife and I stayed at Alexandre's condo for the last few days of our 10 day honeymoon, and it was far and away the highlight of our trip. You couldn't ask for a better location on Montmartre. You literally walk right through one of the street markets in the heart of the neighborhood to get to the condo. It was spacious and clean. Alexandre was a great host. He has put together a very helpful book in a few different languages that gives great advice on local gems for restaurants, shopping, entertainment, etc. We tried a few of his recommendations and they were all great, as advertised.
The bed was comfy but is two twins pushed together, not one king-size mattress. Also, there were a couple buttons on the shower handle that kept falling off, and a couple of the stairs leading up to the lofted bedroom were a little loose (granted, I weigh 230 lbs). Montmartre is pretty high up on a hill, but there are stairs that go all the way up so walking to Moulin Rouge and the surrounding neighborhood is easy if you don't mind climbing up and down some stairs. He's on the third level of his building, which means you might need some muscle to get big bags up the stairs, but when we showed up, Alexandre was there to greet us, let us in, help us carry our bags and get settled into his place. Being on the third level also means a great view out the window every morning, so it's all relative. We would absolutely stay at Alexandre's place again and will certainly be recommending it to friends.