Personally, I would be in favor of it because many of the problems we face today, such as Climate Change, require a united world in order to battle. Imagine if a global minimum wage was established or a global tax code for corporations were set in place? Then corporations could no longer use shady tactics to dodge laws and tactics because they would pay the same no matter where they go. We could establish global agreement on combating Climate Change. Hell we could even collaborate for a global space colonization program instead of always fighting each other.
However, the bad side is if corruption seeps its way into a global government. So a global government has potential to do extreme good if function properly, but also extreme bad if corruption seeps in.