Everything's wonderful and nothing is good at all when it comes to life in a shipping container.
Two opinions: "What’s wrong with shipping container housing? Everything."
What you get with a container is cheap structure, if you can use the box-basically as-is. As soon as you remove anything (including the ends) you need to hire welders and buy steel. Architecture is more than structure though and structure on its own is not particularly expensive- especially when you are building a space as small as a shipping container, so the savings here are minimal. Relatively untrained people can build a room that size of simple wood framing in a day without needing to rent a crane or learning how to weld for about the same cost (or less) than buying a used container.
And "What’s not wrong with shipping containers."
There are instances where it might make a lot of sense to build something this way, and there may be cases where someone wants to spend a bit extra to get the shipping container aesthetic. There’s nothing wrong with that. You’re not going to be building a $5,000 home, but you might get something unique that doesn’t look like your neighbor’s place and you might have fun doing it.
If this is your thing, see also, from Places Journal, "The Emergence of Container Urbanism." H/t things magazine.