It can be very positive or very negative. I think home has to build in you confidence in your originality and that uniqueness of your culture. If not, when other kids don't understand why your hair is like that or why you don't wash it every morning like them, or why you are basically different from them (for me it was why do you always wear dresses, does your mom put grease in your hair, our "ward" [the mormon version of a local church] does this or that, and we all know each other from church, why are you the odd man out?)... when all of that comes at the kid, they'll be able to smile and realize that they are the different one, but that doesn't make them the bad one or the wrong one.
Also, I think it teaches you to befriend people who are not like you, and learn how to conduct yourself in different settings. Some black people don't know how to behave in mixed company, and it makes them look bad. Some stuff you would say or do in a room full of family and friends, regardless of color, you should never say or do in a business, church, or stranger setting. Sometimes when everyone looks like you and comes from a similar background, you don't learn those nuances.
The only outstanding negative I see, is that from my experience, I didn't have as much dealing with my own race, and found that even though my mom took great pains to teach us black history and literature and the like, there's a whole different vibe when you hang out in a predominantly black culture. Fortunately, as I grew into adulthood, I got many opportunities to travel and meet a wide variety of people, and now I consider myself pretty well-rounded and comfortable both in my own skin and with other people in most settings.