Hubs and I picked this hotel based on its proximity to the Museum of Modern Art, and on price. It was priced well below other similar hotels in that neighbourhood, so we booked it. We were extremely pleased with our choice! While this hotel won't bowl you over with its exterior looks, don't be put off by that. The location is fantastic! Ste Catherine street is just a few blocks walk, as is Concordia, McGill and the Museum. There are lots of depanneurs and grocery stores if you want to stock up on food and/or drinks. All sorts of restaurants are nearby. You can just park your car and never need to use it for the duration of your stay. And while you are right downtown, the street is actually nice and quiet with very little street noise.
Our room was very clean and had all the amenities we needed; a lovely kitchenette (with granite countertop, convection oven, full fridge, dishwasher and of course, dishes), a big flat screen TV, free wi-wifi, a generous balcony with lovely views, a really comfy bed with lots of pillows, and windows that open! (this is a must for me!).
The service was perfect. Checkin was quick and easy as was the checkout. When we first checked in, the front desk staff phoned us to make sure we were satisfied with our room. What a nice touch!
There is convenient underground parking available (for a fee, of course) which was really handy. Please be warned though that it will only accomodate vehicles up to 5'6" in height!
I have very little to complain about with this hotel. The only improvements I can think of would be to have recycling bins in the rooms and also to accomodate adult only times at the pool. Unfortunately their pool, while nice, is quite small and of course very popular with families. All it takes is 2 or more families with young children to use the pool at once and well, it's just mayhem with kids screaming and jumping in and out of the pool. It was not very pleasant.
We didn't eat breakfast at the hotel so I cannot comment on that.
All in all, the Marriott R.I. made our last stay in Montreal very pleasant and I would not hesitate to return to this hotel for any future visits to this marvellous city.

I like cmpfigueroa's description "Respectable option"
Good location. Comfortable rooms. Not your Westin or Ritz Carlton but an OK place to stay for a couple of nights. Rooms clean and tidy. Breakfast very good. Good location . No complaints.

Stayed here for 3 nights. I used my Marriott points and this one was the cheapest option among all Marriotts in Montreal (minus the one by the airport, which wasn't an option). Just outside of DT of Montreal, 2 blocks from St. Catherine Street. Service was nice, but room needed some renovation. Breakfast was average. First day I had a major issue with a cigarette smoke coming from bathroom's air duct. I complained to front desk and it was taken care of. Overall, not bad if you are on budget.

The Residence Inn Westmount is on a residential and quiet street a few hundred meters from Westmount Mall and Atwater station of the Montreal metro. It is considered to be just right outside Montreal's downtown. If you're fine with that, then the Residence Inn is a nice option.

Location: 5 minute walk to Atwater station, and to a mall that has several restaurants, a huge supermarket, and the usual shops;

Room: A typical serviced apartment with kitchen facilities
Breakfast was free and respectable.

Service was topnotch.