The apartment we got was great — freshly cleaned and it seemed like it was newly renovated and decorated. It has everything you'd need, including a fully furnished kitchenette with a dishwasher.
Our only issues were finding the correct building to enter at first, and communication via the chat (while very friendly) was exasperating at times as the chat agents are not even located in Montreal, so the help rendered is either delayed or not helpful.
That said, Sonder operates somewhere in between what you'd expect from an Airbnb and a hotel. Not quite one or the other, but we really appreciated the space!
The restaurant it faces does create some noise but didn't bother us as much. Would have loved to keep the windows open without the noise though.
All in all, cleanliness was great, and the heaters were thoughtfully placed. Would have appreciated the air conditioner being in the bedroom so we didn't have to keep the door open but not a huge biggie.