How do problems created by a federal guaranteed jobs programs compare with the benefits of such a program?
It is impossible to know this for sure without knowing details of the particular plan. However, I would argue that the problems would outweigh the gains.
The benefit of such a program would be a massive decrease in unemployment. This might go along with an increase in consumer confidence which would lead to a rise in consumption.
However, the problems would be significant. There would, first of all, be the problem of funding the program. Any program that would guarantee employment to everyone would be massively expensive, leading to increases in any existing deficit. In addition, such a program would be likely to lead to inflationary pressures as the unemployment dropped near to zero. Finally, the government would have a hard time finding an "exit strategy." Ending the program might plunge people back into unemployment while continuing it indefinitely would be too costly.