As written by many others, this is a very good place to stay! The location is perfect, quite close to restaurants, bars, etc. I managed to walk to all the places I wanted to see in Montreal during my weekend stay.
Fatine & Christopher are very kind hosts. Check-in was quite easy, I could leave luggage since I had an evening flight, everything you need is provided - they even offer coffee, tea, and cereals for breakfest, if you like. I had the feeling to be welcome at any time. They do have a good list of recommendations for restaurants and sights as well. I did not manage to try them all during my rather short stay.
The apartment is very clean, even though they have three rooms which they rent out. I did not have any troubles with the single bathroom, as others stated, but that probably depends on the group sharing the apartment with you. Respond time is very fast and well organized - so you get all the information you need right after booking and shortly prior to check-in.
So yes, I'd recommend staying at their place - and would do so again, too!