Yes, people make houses out of them. I have seen several shows on tv about guys doing this and it just leaves me scratching my head. Bear in mind, I am, if I do say so, an expert wood worker and have built 8 custom log cabins. Plus have years of experience with framing.
So these guys get three of these things and set them up in a horseshoe shape. Well and good they have some pretty good square feet and a roof that won't leak. Now the problems start. You have to weld the 3 containers together. You have to make openings for doors and windows. Lots of welding there. You have to cover the inside and outside with some kind of sheet rock and or wood, you have to frame up the inside in order to put on the sheet rock. If you want a roof overhang, you have to put a roof on. By the time you are done it would be more work than just building a framed structure in the first place.
Still seems like a good idea for a woodshed to me.