It's a complex episode that epitomises the very best of Star Trek writing.
However, what is telling is how a minority of fans think that because Neelix and Tuvok died in an accident, Tuvix needs to die in order to set that right.
Morally, I think it is wrong to sacrifice Tuvix and that they are a living being with a right to exist regardless of what accidents and what deaths preceded their creation. If I was in Janeway's position I wouldn't have made her choice, but I can understand why some people might have, and consequently been terribly haunted by their own decision. Though I would still disagree with it.