A good effect is that robots can, have and will replace many dangerous human jobs, which in turn will save lives. A bad effect is that those people will end up out of a job.
Well maybe we can deploy robots on dangerous jobs. It is a better idea to put them into those jobs because it is a risk to ones life. Replacing robots to manpower will increase production and the company will earn more. But like what you said, many people will end up losing their jobs.