If you want to make a quality repair that will last a long time, this is the product to use.  I used to be a big fan of Shoe Goo, but the fact is that the repairs never lasted too long and were never good for building up the sole. This Freesole urethane is REALLY tough and adheres extremely well.

A couple cautions, however:
1. The product will seep through even the smallest hole or crack...mainly because it takes a long time to dry/cure.  But, there is a solution:  buy the Cotrol accelerator (also made by McNett). This thickens the product and causes it to dry/cure in about 2 hours.  For some reason Cotrol is not necessarily sold at the same places Freesole is sold, so they may have to be ordered separately.

2. If you use Freesole to build up the a worn heal, be aware that it will dry/cure to a very smooth and slippery surface.  I put some rice on the surface after it had started to set.  The rice disappears after you use the shoe a bit and you are left with a rougher surface that will not so easily result in an unexpected slip.