Honestly we've had almost no problems. We live in a very small town with very few non-white people, but honestly everyone is very good to Yuna and treat her no differently than the other little kids in town (who are almost all white).
The one person we had trouble with initially was my aunt. She is probably somewhat prejudiced against black people, and when we first adopted Yuna she said some extremely venomous and nasty things about Yuna and about us.
Over time, her attitude has changed, and I believe she really does love Yuna now and has come to see the error of her ways.
I am not sure what will happen with any future children, but I think she will be easier to deal with.