It's split about 50-50 here, and I've had a lot of Marans roosters. I have culled several nasty, nasty boys, but I also have some real sweeties. I have a very mild-mannered black copper rooster (and it's a good thing, 'cause he's the most ginormous bird I've ever had!
). I have a very nice cuckoo boy that lives in the same pen as a white rooster. Both are very sweet to people and to each other. Then I have a golden cuckoo rooster, a young one, that just decided about two days ago that he'd try to take my leg off every time I walked into the pen.
All of my Marans, regardless of their attitudes toward people, have made
excellent flock protectors. They take their rooster-ing job very seriously!
I've never had a hen I didn't like, personality-wise. All of them have been nice girls, never aggressive.
Unless they are sitting on eggs. You endanger life and limb messin' with one of those girls if they're full-on broody!!
But they make excellent broody hens and great mothers, if you let them set.
My whole point being, personality is really going to vary, especially with the roosters--and with them, you likely won't know what you've got 'till they've reached maturity. Most of mine didn't exhibit aggression 'till they started noticing the ladies. And no, they are not quiet. I wouldn't say they are worse than any other large fowl breed--but plenty of crowing and plenty of normal chicken noises.