The positive effects were that they were allowed to easily assimilate and become a part of the American society according to American traditions. They were given all rights that all other citizens of the United States had which meant that they could vote or purchase property or anything similar.
The negative effects are that in assimilating them they would often abandon their own culture in order to adapt so they were not included as so much as assimilated. The idea was not to make the two cultures co-exist, but rather have the Native Americans become like the everyday US citizens.
