Child labor during the industrial revolution, increased family income and thus improved the over-all life-style of the family.  The first activists to oppose child-labor were adult, male laborers who were trying to reduce the number of people in the factory labor force so that factory owners would have to pay them higher wages.

I agree with the first answer.  But I would add one thing.

The first answer says we have to remember that those days were not like today and so we must not hold them to our values.  But we also have to compare those days to what came before.

It is true that kids had always been expected to work.  But before the Industrial Revolution, that work had always happened at home, within the context of the family's work (farming, mostly, but other things too).

Once industrialization came, the kids were expected to work, but now they were working away from their family and under the supervision of strangers.

This put stress on the families because it was a very different social situation than had existed before.

It's important to remember that we look at child labor as immoral and unethical for companies to practice or parents to allow, so much so that we outlawed it early in the 20th century. At that time, during the Industrial Revolution and into the early 1900s, people viewed it as a fact of life, as one of the few ways a family, especially an immigrant family, could earn enough to survive.  Education had much less value than working did. 

So the way it affected society was that it denied children education, was dangerous to them physically, and put further stress and strain on the family unit as individual members were isolated and separated day to day.  There were labor activists fairly early on in the industrial revolution, but they were shouted down, beaten down or made illegal into the late 19th century, and achieved almost no success at all.