Soy milk–good or bad?

I have been giving my son, 15 months, soy milk every since he was 13 months. We just stopped breastfeeding last week, but we have been slowly cutting it out over 5 months) We did whole milk but then I read a lot about the negatives of feeding cow’s milk (we are the only species that drink another mammal’s milk, etc, and it is not good), but now people are saying negative things about soy milk and I want to know the truth. I would like some real hard evidence one way or the other. I may try rice milk next(until someone finds something wrong with this).
Is it bad for little boys? I read it can affect their development.
I would like to add…I am not experimenting with my child! Previously, everything I have read said soy milk would be great and my Dr said that was fine. now, there are more studies coming out. I just wanted to get to the bottom of it. There are negatives associated with whole milk as well. But for those that gave good advice, I appreciate it. I drink soy milk myself but may consider switching back as well.