the answer is no he is not a good person nor a smart person and is a punisher style narcissist. The reason is based on what he does, the limitations of his powers, and his naïve world view.

The people he murders are in two categories.
1 criminals that are convicted and
2. people in his way.

the problem with 1 is that those people are already in custody and being given society's punishment. he is just going over the top of that to give his decided judgment which is death. for number 2 those people are generally good people and thus a murderer to make it so he can continue his judgments. He believes his judgment is above other government or peers as again they are being punished he just overrides them. The problem light has from being any good or the god he hopes to be is he lacks omniscience. Criminals that are convicted could be innocent. criminals not caught can be unpunished. he has no way to know if he is meeting out his judgments correctly and this is the hugest flaw in his world view. he believes him being god will make the world a better place however his lack omniscience destroys that. sure crimes rate would initially go down due to fear but the moment someone discovers his murder or crimes are unpunished he know he can continue. and God gets torn down as uncaring or lack of action means the murders are divine providence. The system falls as misinformation, false conviction, divine murderers start happening with a god that can't determine who should be kill and who shouldn't. It turns into a murdering mess and at the end of he only sows chaos. light doesn't seem to realize this and so I describe him as a punisher styled narcissist.