Thanks to this thread, I had my parents use this app when we arrived into YYC this past weekend. As a NEXUS card holder, I wasn't beside them as they went through their entry procedures at YYC but the key benefit seemed to be that there was a designated lane for arriving passengers with the ArriveCan app. So even if it doesn't really save that much time once you are at the kiosk and even if you have to go through some of the same procedures when you do not use the app, just being able to be in a smaller queue would make it worthwhile.