as a US citizen, I've seen an improvement on the Canadian clearance. The only headache is if your flight runs late (after midnight) and you land around the same time as a bunch of leisure flights returning from Carribbean or Florida. They reduce the staffing and every leisure person seems marked as a revenue opportunity and also seems to have problems filling their forms out correctly. I kno understand why my Canadian colleagues are so by the book.

To compare and contrast with the return US side, a couple years ago, there was a buy 2 get 1 free deal on crown royal and the US agent was floored I only bought 1 bottle. I said, "well aren't you allowed only 1 bottle?" to which he replied, "do you know how much paperwork we'd have to do? Next time get the deal!"

It's not an issue now that duty free is after immigration.

All and all I don't mind clearing customs on either side at the new Air Canada terminal at Pearson