Absolutely ideal location for a first time visit to Montreal. You can easily walk to Old Montreal, Plateau and Mile End, the Gay Village. And if you do want to take the metro one of the main hubs - Berri UMAQ is right nearby!
The room is very comfortable and reasonably quiet, though the resident cat was a bit annoying one morning. I think he is moving out soon tho so shouldn't be an issue later on.
One thing to note, since I don't think Air BnB does a good job of making this clear - there are two other guest rooms in the flat (in addition to the host's room) and you will be sharing the hall bathroom with them. It was not an inconvenience during my stay but if you need a lot of time in the bathroom to get ready you might have an issue.
Helpful tip: The airport bus stops about a 7 min walk away from the listing so that is an ideal way to get into town. And if you are just staying for the weekend you can buy a pass that is valid from Fri evening to Mon morning for $13.75 that gives you unlimited travel from and back to the airport, as well as on the buses and the Metro in the city. SUCH good value. You buy the pass at the kiosk inside the airport before boarding the bus.