As the victim of grandma's tom turkey, yes, yes they can be aggressive. Stay out of his personal space yet stand your ground. Walk with a broom. Don't wear shorts.
As the "mother" to 3 poults, no, they aren't mean at all and they follow me like puppies. Might change in the next couple of months. I have a broom handy just in case.
It just depends on the bird, same as roosters. Don't tease him, taunt him, or instigate anything with him. Be calm, stand your ground, but don't get into his space. Let him know you'll leave him alone if he leaves you alone.