Not that bad really.
An occasional slight sting from a hot piece of carbon hitting the face or neck. Just have to make sure you always have glasses on. Also not to wear a white shirt.
It puts some people off but I would rather the carbon on me than wear ear plugs while I shoot.
Some claim that the right hand loads will cut down on the carbon back blast but I couldn't tell you what those loads are.
Stopping power: The power some guns have to make you stop what you are doing and get your wallet out.