Steel sheds, especially at that price point, will buckle and warp in very little time. Any structure used for storage should be hold up to the elements and hostility of mother nature. I just built a custom 12x10 garden shed myself, after looking at dozens of prefab (metal and wood) varieties. 2x6 rafters, 2x4s wall studs, 16 inch stud spacing, 3/4" OSB, and an infinite amount of customizable shelving options should speak volumes. The walls of a steel structure will dent like a tin can.
My neighbour and I both have steel sheds they are are least, 20 years old. I keep the mower and patio things inside it, he uses his for a pool heater. Mine is on a wooden deck, his is on poured concrete. Our winters can be anything from 2" of freezing rain to 2 ft of wet snow. I have never had a problem with mine. His is also in good condition with the exception of needing a little paint above the heat from the heater.