Give yourself at least an hour per box for assembly, and an extra pair of hands makes it go faster. When assembling, the slightly shorter pieces are for the ends, longer pieces are the sides.
Every piece of the metal sides and ends has a plastic film on it that you'll want to remove. It's very hard to spot. I didn't notice it until I had the first one completely assembled, but by then it's too late to remove cleanly... remove before assembly (it's very satisfying!). I'm sure the sun will destroy the protective film in short order and make it look ugly.
Also, these 24" deep boxes will be fine for dwarf fruit trees, berry vines, asparagus, potatoes and sweet potatoes, but they're way too deep for anything else, just a waste of valuable soil, IMO. The only benefit I see is that because they're taller, they're easier to access if you have trouble bending low to work your garden.
Other than those things, these are nice looking beds and I plan to fill my garden space with them (the 12" high ones mostly).