We stayed at Stewie's for a bachelor party. The place was a little bit further away from downtown than advertised, as it is about 20-25 minutes away. The neighborhood is a little grim, but it was quiet and felt like a safe area.
The place was very clean and had everything we needed. Stewie was very fast with communication every time I reached out to him and was a very gracious host. The place was a little smaller than anticipated. I wouldn't recommend trying to sleep more than 12 people there.
I personally would probably try to find a place a little closer to downtown if I returned to Montreal. If you do not care about being 20 minutes away from downtown then I would definitely recommend this place to you.