The apartment is lovely, clean, in good repair, and super accessible to tourist destinations, shops, restaurants, etc. in Old Quebec. We enjoyed that very much.
However, there's no sound insulation, and both the building and the area are quite noisy. You can clearly hear neighbors walking around in the apartment above, the radio in the apartment next door, and footsteps coming up or down the stairs. You can hear tons of noise from the street, including anyone having a conversation below. There's an Irish pub next door that had live music every night we were there (Thursday through Sunday), and that was not only audible but *loud* from within the apartment. Even after the live music stopped around midnight, they put on some clubby music, and between that and the clusters of people coming, going, or hanging around on the street below, I didn't get to sleep until 2 or 3 am the whole time we were there.
The apartment is lovely and spacious, and can sleep quite a few people. If you're coming with a group and plan to be out partying every night, this would be the perfect place to stay. But if you're hoping to get a good night's sleep, I would look elsewhere!