Not a new concept. There is a container cabin for sale in the classifieds for a real decent price.
The particular example in this thread does not appear quick at all and the finished project is not mobile. In addition the shipping containers are not designed to be partially buried as pictured. He's also created a vapor trap in the walls that will eventually result in mold in the walls/ceiling. Whoever put this together put a ton of work into it and finished the inside very nicely, though.
For the work and expense involved I could have built (and did build) a real nice conventional cabin on a pier and beam foundation that would add much more value to the property.