The bixi bike system is tremendous. Me and my wife have been on four separate trips already today, and can't believe the convenience and value of the system. The bikes themselves are good enough and rugged, with three gears and sturdy tires. There are stations almost everywhere, so staying under the half hour limit is not much of a problem. The best ride we had today was from Jean-Drapeau Island to the other island next to it (the one with the casino) and then back into town over the other bridge (the southern one) and through the port area. The ride was scenic and tons of fun, but it does take about an hour so you are going to pay the little fee it costs to keep the bike an extra thirty minutes.
Great work Montreal!