That is a pretty interesting question. Do I get to assume that I would still have been born? Can I assume I would have been born to the same family and lived in Sweden where some of my ancestors came from? I think if that is the case, I might say unequivocally that it was bad. But I've had a pretty good time here in the New World, so it is difficult to say that.
From an historical perspective, it is also pretty difficult to answer that question. Obviously horrible things were done, the spread of disease that killed millions of natives and the incredibly callous and destructive attitude of the colonists (some of them) towards the natives and the resources of the New World, the loss of incredibly advanced cultures and ways of living (The Iriquois and other Native American groups) that likely set us back quite a ways in terms of the level of civilization... Anyway, you can certainly make the argument that it was a very, very bad thing.
But you might also suggest that it was good because it led to a certain level of religious freedom, a country where social mobility was far more open (of course only for certain groups of people and you can make the argument that since then it has decreased) and the development of the democracy that many folks feel is pretty darn good (even now with its warts...)
So I would have to say that in my opinion, this is a question I am not going to be able to come down on one side of, perhaps if you added a few more limitations to the ways you could interpret it.