I will say that outside of "Gee, look at this new method to keep stuff cold!", the idea of the, I assume, waterproof and element resistant container is good, not that you can't buy underground storage tanks and whatnot and do the same thing. I think here you're paying for both new, and the convenience of molded-in steps and whatnot. Makes for cleaner food storage as well as animal resistance. I've seen some nasty examples of home built root cellars.
Depending on price, I'd consider a "drop-in" before digging my own.