Couple of 'em are ok, most are way too "sharp" with too many sharp edges, especially in the area where the keyboard would be (and most people may rest their arms against).
Obviously the last one, the concept with Bill Gates sitting at it, that's the big winner... would be awesome to have something like that but, I'll be 80 years old before it's commonplace I'd say.
Some of them are extremely expensive. Some look downright dangerous. I feel like most are more of a novelty than actually being as practical as modular alternatives.