Right about where I expected them to be. Low 30's for busiest in the world it certainly has that international feel and is easily the busiest and biggest in Canada, what with Toronto being the largest city.
Some things I noticed while travelling here from California. Customs was great coming in, though the only real issue they have is when some flights from say China or the Far East come with 400 passengers. Luckily I just snuck after one landed and they were waiting in baggage so I waltzed right in, declaring my weapons and intent.
The walk from arrival to customs, to baggage to parking was a little long, but I go longer than normal without stretching my legs. Parking has that tap system which I really really like and we were home to Hamilton in a breeze, though with travel on the 23rd the roads were clear too.
My leaving experience was that the departure drop off seemed really long. The automation of check in and bag check is almost as slow for most people unless you know what your doing. Again with the long walk to the gates. Customs was great, a lot slower for me with a more popular flight departure time I saw a lot more variety in documents. I liked the customs check in kiosks as filling out paperwork sucks. They were quite strict on the no phones in line policy.
Shopping and duty free seemed kind of clustered and not well laid out, prices weren't quite what I expected as well as variety. They could use more bathrooms. Their intercom system is so loud me using headphones to block sound out was useless. Hopefully I'll have my Global Traveller pass by the time I plan to come back here. I do wish more places used the body scanners.