Had it free on TK (YYZ-IST) a couple of weeks go, but never had it work on LH equipped planes. Use it all the time on AA domestic flights (though had a dozen free use vouchers) but there's no infrastructure here in Canada because the market is too sparse, and the technology is moving from land based relay to satellite based systems. AC had it on some LAX flights (since they fly over the US for most of the flight) but the take up rate was minimal. So AC is no further behind than most overseas carriers who have been waiting for a provable technology (Boeing offered a version five years ago that flopped because there was not enough demand, and there were technical problems) which appears now to have arrived.
The next generation of IFE is going to include internal wifi that will feed entertainment and web access to everyone with their own tablet, laptop or smart phone. This will be cheaper and lighter weight than the wired IFE we know today.