The obviously effects the economy by canceling out jobs but also means that if for some reason the machines stopped working then we would be left with no-one skilled enough to fill the holes.
Another issue is that the more machines we rely on the more the world becomes unindividualistic.
Machines can only make things one way, every product outputted will be the same, ones not the same will be filtered out by quality control. In the past every item you purchased was in some way, individual and a piece on unto itself.
Hope that gives you a few things to think about!