I do not know what your particular textbook says and you probably ought to look in it for the exact answer that you are expected to put on the exam.
To me, the disadvantages of productivity improvement are closely tied to the disadvantages of capitalism in general because capitalism and productivity improvement go hand in hand.
When productivity improves, people in that industry tend to lose their jobs. This is certainly a disadvantage. As productivity improves, there comes to be a race between firms to cut costs and gain profits. This leads, in the modern, world, to outsourcing. Outsourcing is certainly a problem for the people whose jobs are lost.