Not sure if there just isn't a lot of travel through here, but there were not many people when I arrived to YUL in either direction. Customs coming in was amazingly fast and convenient. No line at the cab stand. ATMs right after customs so I could grab some Canadian cash.
Check-in for departure was a breeze - no line. I thought it interesting that they have self baggage check where you put it in the machine yourself, but whatevs. Security was a breeze - almost no line. I should mention they have a separate check-in and security for US-bound flights (AMERICA!!). YUL is a pre-approved screening airport for entrance into the US, so you actually go through US customs right after the security line. And that was incredibly convenient and fast. And that also meant not having to go through customs in Detroit.
Employees were friendly (it's Canada - duh), and the airport was generally clean and had enough shops. I'm a fan.