Our family (parents and two girls aged 8 and 9) stayed in this apartment for two nights.
The unit was very clean, well-appointed and spacious. The beds were comfortable and the blackout curtains worked well. Sarah was very responsive and helpful, offering many suggestions and recommendations. We didn't use the kitchen but it seemed well-equipped.
The obvious benefit of staying here is the location - right on Place Jacques Cartier which is the heart of Old Montreal and walking distance to plenty of restaurants and attractions. This worked well for us because we were only in Montreal for a short period of time and therefore wanted to minimize travel time between our accommodation and activities.
As mentioned in many of the other reviews, we did experience noise late at night given the location. There are two sources of noise: 1) street musicians who set up across the street and play with the help of a speaker, and 2) the thumping bassline from the speakers in the pub just below. Earplugs helped to minimize the first source but didn't do much about the second. We stayed on a Tuesday and Wednesday night in August. On the Tuesday night both the street musician and the bass from the pub stopped around 11:00, while on Wednesday the pub speakers were quiet by 9:00 and the musician was done by 10:00. So it wasn't consistent, and we suspect the duration of the noise varies throughout the days of the week and throughout the months of the year. But if someone prefers going to bed early and has a hard time falling asleep with noise - they may want to consider a quieter spot in a less-ideal location.
For our family, the location far outweighed the noise and we were very happy with our stay and would highly recommend it.