Eh, personally I think a citizen going around stopping crime is a good thing if they have the means and don't ruin cases. In Batman's case, he is a billionaire genius and not operating in our world, so he gets a pass.

There was actually a article I read about real-life vigilante super-heroes (martial arts trained) people in one city. They didn't go out of their way to find stuff, their martial arts were focused on disabling and they used pepper spray instead of guns. I think this is a good thing as it is one more person keeping people safe. If they overstepped their bounds, I would say that is a bad thing, but not vigilantism as a whole.

Hell, police step out of bounds a hella lot and I still see them as a good thing.

My own philosophy is 'as long as you are doing more good than bad, and not doing something permanent (aka killing someone, which if you were wrong about the situation means you took a innocent life, and even at the best you have taken the choice to become good from that person. There are a lot of examples of people doing horrible things in their youth only to turn around and become saints... so that is why I lean on the 'no kill' side).