While in Montreal we have been using the public transit system to get around rather than driving our car. We have to say that we have taken public transit in many US Cities (we are also past public transit drivers in Western MA) and this transit system has been the easiest to navigate.
The bus and metro system is so expansive in Québec that you can get anywhere efficiently. The buses run regularly and we never waited more than five minutes in the metro stations. The cost for a three day pass was $18 which makes it a cost saver when looking at the price of parking!
The other amazing aspect about this transit system is that a few days ago I emailed customer service with a question regarding the Opus Pass and they emailed me back within 12 hours! I have never had that happen with any other transit system! Kudos to STM!