Some positives:
-inexpensive
-sturdy
-sized for transport
-security
-fire resistant
-mobile
-easy to partially bury
Some Negatives:
-difficult to insulate
-difficult to avoid rust and condensation in humid areas
-difficult to install doors and windows
-difficult for cellular reception
-difficult to expand on
-difficult to fit furniture due to non-standard sizing
-requires special skills and tools for connections such as plumbing and electrical
-electrical conductivity could be a risk
add to the positives that they’re designed to be stackable.