well I think robots can be good in replacing human jobs when it comes to speed and robots don't need to rest and eat. The negative result of it is there is a high chance of people who are unemployed. Lots of people lost income if that happens.
Right because robots are more effective than human, now it is easy to take a lot of work from robots with short time. They are not in need of food and rest as you said so they can work for the whole day, but the problem that we will face is that we will have to take risk as if they will not be properly programmed then they will spoil all of our effort and our investment.