About to try a "script coverage" service

The James A. Humphrey of Humphrey Edwards Films has finished writing a new "full length" feature script. It is not my first one but I have never sold one. This time, I plan to do it a little differently and try a "script coverage" service. I have never tried a service before. For those of you that have never heard of this type service, it is simple. People with differing degrees of scriptwriting expertise offer this service at differing costs. They read and critique your script before you submit that script for sale. I am not going to share which service I am hiring but will share my thoughts on the results. The plan is to consider the critique and rewrite the script to reflect their input. Upon completion, I will attempt to submit the script to Writers Guild of America recognized agents.