My wife and I stayed at Chateau de l'Argoat in December 2012, and it was a nice experience in the midst of nasty, slushy weather.
The hotel is very conveniently located; my wife and I love walking, and we found all the main areas of Montreal accessible by foot. Notre Dame Basilica was only about 25 minutes away for us, for reference. We drove up from Toronto, and it was very nice and rare to find a hotel in a good location with parking. FREE parking. The lot is in the back, out of the way and in no danger of the being covered up with snow, unlike the majority of cars we saw parked on the street in Montreal. The parking lot is in the back of the hotel, though, and a bit hard to find; it's better to be approaching the hotel driving eastward. After passing the hotel, there will be a small side street. Assuming you are headed east, turn onto that road, then immediately turn right on the first little side-street. It's a steep road, so if there is ice, be very careful. Also, GPS users might not be taken to the right place if you just follow the unit's directions; mine messed up the location.
The room was large, and though a bit outdated, very comfortable. The carpet probably needs to be replaced, though. The bathroom was great; we stayed in a Queen room, and the tub was very large, and perfect for an evening soak after a long day of being wet outside. It's one of the best bathtubs I've found in a hotel aside from one with an actual Jacuzzi or whatnot. The soaps the hotel provided were actually soap, and high-quality; my wife and I loved the lavender-scented one.
The staff were very friendly; they greeted us every time we entered the hotel and came down for breakfast.
The morning breakfast was great; Montreal bagels and other tasty breads. The coffee was so-so, but not bad compared to most places that just serve instant or Folgers. I requested two bagels every morning and they were perfectly toasted. Other than that, nothing special, but it's a free continental breakfast; what more do you need?
Very importantly, the hotel was very quiet. It's by a major road, but we couldn't hear anything, and I slept very well all three nights. I'm a light, sensitive sleeper, so this is very important for me. I don't know how the rooms next to the road would have been, but if you are a light sleeper request a room facing the parking lot.
The Internet was free and reasonably fast. No complaints there.
All in all, a great place to stay in Montreal, and when we return, we will most likely stay at the Chateau again. I highly recommend it.