A nice place for a short visit. I would describe it as a bedroom with a bathroom and half kitchen.
My only gripe would be that the walls are particularly thin, meaning that you can hear walking, etc. from the unit above you and from people in the hallway/stairwell outside the room. I was fine with this, but I can imagine it being uncomfortable for some.
Despite the space being small, staying in Le Plateau and right next to Mont-Royal station means you have a great place to explore and easy access to the rest of Montreal by metro.