This was one of the most readable non-fiction books I've ever come across. It's written in clear effective English and makes its point (mainly through repetition) very well.
Thurow has one basic idea - that the American economy was paralysed in the 1970s because of the variety of groups (upper-class versus lower-class, blacks versus whites, industrial versus agricultural etc.) with conflicting interests that made it impossible for the government to undertake effective policies. As such, this book seems pretty commonsensical and hardly revolutionary nor particularly enlightening. Thurow takes us through the various economic problems that the US faced at the time to show how this is the case.
This problem appears to be the combined flaw of democracy - that people have a say in how the country is run - although he didn't explore that; and capitalism - the doctrine of self-interest. The groups all want to protect themselves. This means that any change will inevitably be vetoed/subject to prolonged protest by at least one group - namely, the group that will have to suffer (by seeing their incomes decline) so that the rest of the economy can benefit. This shows up in the protection of inefficient industries such as steel and textiles, the unwillingness to impose strict income and price controls etc. In effect, the economy will continue to stay stagnant until certain groups are imposed on for the sake of everyone else.
He also makes the interesting case that inflation was not really a problem, backing this up with statistics that show that the average American's standard of living rose; and income differences didn't widen. Rather, it was a matter of perception and psychology.