Not sure why everyone's complaining. You pay for bus service but you're expecting limo service. I took this from Toronto to Montreal. Last I checked, buses don't defy city traffic which is the reason why the bus is late sometimes.
Anyways, the buses are clean and there's ample space. Wifi is shotty so bring something to keep you busy. My seat had no USB charging port if that matters to anyone. If you are leaving or arriving during rush hour, expect to be late. If these things matter for you, I would suggest you find an alternative but there won't be anything as cheap as Megabus to Montreal.
The bus quality is similar to GO transit buses.
p.s. Don't be the person who sits on their phone the whole time, no one else is interested in your life story.