The location is absolutely amazing! Within walking distance to basically everything we wanted to see and we didn't even need to drive while in Montreal. Check-in was a smooth process and the hosts were quick to reply to messages and even gave us parking recommendations. We parked in an underground parking lot which was $20 for overnight parking and a 5 min walk to the apartment.
The only thing is that the building is very old. You can't tell from the photos because they've decorated the apartments nicely but in-person you can definitely see the age. There are some cracks the wall, the wallpaper is peeling a bit and the bed covers, bedsheets and pillows are definitely worn down and were not very comfortable. There's no fan in the bathroom either so I imagine that you might have problems with odour if you're staying for a long period of time. I only stayed for two nights so had no problems with that.
The other issue I had was with the AC, the AC is right next to the bed and very very loud. I'm a lighter sleeper so I had trouble sleeping because it was so loud but you had to have it on or it would be too hot. Opening the window wasn't an option because you're on the first floor so you can hear everything happening on the streets.
Overall, I think staying here for a few nights is fine if your main goal is to explore the city and be in a convenient location.