I stayed at William's for over a month and everything went well. When it was very hot William left me a fan and when it started to get cold he left me an extra radiator.
He is always thoughtful and helps you with anything you need. He's a great guy who takes what he does seriously.
The flat is shared with two other roommates who, at least when I was there, lived there permanently. I didn't have any problems with them, they were very kind.
The room is very big and allows you to work. Just as a detail: when I arrived the room didn't have a plug near the desk but William, without me asking him, installed two plugs next to the desk so that I could work as best as possible.
The location of the house is unbeatable. It's downtown, very close to the subway line and with a Street Car stop in front of the house. The neighborhood is very good and there is a laundromat 2 minutes walk away.
To conclude, recommended for long (and short) stays in Toronto.