Half the power consumption, quieter, infinite speed control and potentially a longer service life. They are also known as Electronically Commutated Motors (ECM). They use a microprocessor, as opposed to carbon brushes to phase the coils...they also use permanent magnets.
In my business (HVAC), they have pretty well taken over as blower motors in forced air furnaces. In fact, the Ont gov't (IESO) used to cut you a cheque for $650 if you installed a new furnace with an ECM blower...to encourage you to use less electricity.
Agree with Akrisoner, considering the Garmin Force TM (brushless) is in the $5k range, I think you're going to see a big increase in pricing from MinnKota.