Before booking, the host told us that the internet was fast and reliable, but it ended up being down twice for multiple days in a row each time, causing us to miss several days of work. With the router being located in a different apartment in the same building, the signal was also relatively weak causing the internet speeds to randomly drop throughout the day. The host made some changes towards the end of our stay which produced slightly better speeds and reliability, but I still wouldn't recommend it for work.
The apartment did not seem to be properly cleaned before our arrival -- we found dust on surfaces, old trash in one of the trash cans and we had to wash most of the dishes in the kitchen cupboards before using them.
The apartment is within walking distance of most attractions in downtown/vieux-québec with easy access to public transportation, so I would recommend it for people planning on spending all of their time out and about, but not for those planning on working and spending time in it like we did.