Compared to brushed-motors they can be more powerful for the same weight (which is why they are popular in the RC world), quieter, last longer, and produce less EM interference.
The downside being they need powerful rare earth permanent magnets to work, making their construction more expensive than induction or brushed universal motors.
https://www.youtube.com/watch?v=bCEiOnuODac
Compared to brushed-motors they can be more powerful for the same weight (which is why they are popular in the RC world), quieter, last longer, and produce less EM interference.