Not sure what it would be useful for, other than a "mine's bigger'n yours" gun, the cartridge length isn't longer than the .45acp, so it still wouldn't be legal for deer hunting in several states whether it's ethically powerful enough to use or not. I don't know that it'd tickle my fancy:

For that kind of money I could buy a PAIR of Desert Eagle .50AE's that are considerably stouter than the specs I've seen for the GI...not to mention the bbl swap platform.

I guess there should be some contender against the Desert Eagle though, it would be nice to make HEAVY pistols a bit more common and cheaper...maybe start a new class of IPSC like super major categories or something, a .50 bore class! Might be fun.