Can anyone tell me about traveling by train from NY to Toronto?

I am considering going from NY to Toronto by train in a couple of weeks. Has anyone done this trip and if so: is it a nice trip?

What happens at the border, do I have to get off and walk through customs/border checks or can I remain in my seat (broken leg – the less walking the better at the moment)? If I have to get off, do I get off both on the US side when leaving the US to show my passport etc as well as on the Canadian side when entering Canada?