When a Shield is all you have, it works better than nothing in the home. Could it be adequate? Sure, as good as a small revolver. Given an option or choice, there are certainly better home defense guns than a Shield.
A compact gun designed for concealment will not be as effective as a larger, higher capacity, heavier, easier to shoot gun for home defense, especially when adding accessories such as a light/laser or extended magazine.
If one owns a full-size, high capacity defensive pistol, I doubt one would default to the Shield if the other was available.
The only excuse for using the Shield is if you have no alternative.