The correct answer is: Voters have a wider choice of candidates and ideas.
In a bi party system there are only 2 options which in general have a very narrow ideology and therefore divide a country. As a voter you may not feel identified with any of them. When more parties participate, different ideologies are represented and those voters have a greater probability to find one that suits them. Also they have more chance that their ideas are represented in Congress.
Answer:
It depends on what you have been taught, but I would personally say negative because of the diseases that destroyed Native Americans and the rise of slavery.
On the flip side, if you're thinking of positive, it did help exchange new ideas and goods (the Columbian Exchange) between the worlds. It also allowed a safe haven for those persecuted (like the Protestants) and allowed countries to dump their inmates onto the new land.
