I fly out of Pierre Elliott Trudeau whenever I fly to my destination and for the most part I don't have any issues. I've gone to Canada Customs to register some products for travel and they were helpful. When I do the pre-clearance US check at PET Airport (which is somewhat rare because generally I have a stopover in Toronto or Vancouver when I fly to the US), I don't have any issues.
There is a city bus that services this bus which makes travel to/from this airport somewhat easy depending on the location.
The WiFi is free and they don't charge for the luggage carts like some airports that I've been to do.
I would give 4 stars.