Admittedly I haven't tried those bikes but I imagine 90USD buys you a 90USD bike and the quality that goes with it. Boris/Citi/Bixi bikes cost considerably more but are incredibly robust.
They break really, really quickly. Almost half of the ones i've ridden have had something broken. And not seemingly from abuse or collisions or anything, just stuff falling apart. Bad brakes, broken shifters, snapped off seat adjusters(the metal feels soda can cheap), bits just falling off from sheered off metal, etc.