I've never traded them myself since the basic math of it puts the odds in favour of the house (broker) for each bet, meaning you have to be right far more often than your wrong in order to make a consistent profit (like 70%+ of the time.)
I also don't know any career traders (personally that is) who trade them as part of their main business.
That's not to say they aren't fun to bet with... just be very aware of how the broker makes money off them and, in turn, how they are structured for payout.
