Was Thomas Edison's influence good or bad?

Depends on how you define, "negative impact."

Edison was a vigorous, sometimes ruthless, businessman, and his efforts to maintain a monopolistic hold on technologies he thought were "his" (electrical distribution and movie making, for example) probably delayed non-Edison ideas from flourishing for a few years. The "Battle of the Currents" is an example of how Edison fought to maintain control, and thus delayed the implementation of AC power. However, in most cases, popular demand simply overcame Edison's efforts.

Edison was quite proud of the fact that he never worked on any weapons.