Should you do a postdoc?

Only if you have realistic expectations of what it may lead to. For the average postdoc there is only a small likelihood that it will lead to a permanent academic position. It is worth looking at the talk Challenges being faced by postdoctoral scholars in Canada. (Is it an "academic parking lot"?). Although focussed on Canada most of the issues are relevant world wide.
Ultimately, this is a very personal decision dependent on your own values and goals. But it should be a well informed decision.