This was the most pleasant step of the whole process. I read the info here and was pretty much prepared. I came in at 9:00 am for a 10:00 am interview. No line at the entrance but more people were sitting inside on both immigrant and non immigrant visa sides. Everything was pretty much as per description here, except that yes they do have the receptionist now right in front of the elevator who checks your appointment letter, gives you the number and tells you where to sit. You then wait for your number to be called. It was probably 10 mins at the window to submit documents and 10 mins of interview. Both the woman and the man from each window were very nice and my visa was approved. I was asked how we met? how have we been seeing each other for past year? what does my spouse do?
My only frustration was the long wait till my number was called to each window. I came upstairs at 9:15 and left the consulate at almost 12:00. Most of the time I was just sitting and waiting. But it seems like they did get through almost everyone before lunch, as when I was leaving the waiting room was almost empty.
Good luck to you all! Enjoy Montreal while you're there