From my experience with some amount of traveling, I would agree that its very nice to use in practice and definitely got a lot of things right.
Modern US receptacles are “tamper resistant” and are required by code in places that kids can get to, and they have similar safety shutters. Unfortunately, many of them, especially the cheaper ones, suck and actively eject plugs.
The lack of insulation on US plugs to prevent shock when plugging and unplugging is a fair criticism. I suspect this is mostly because US prongs are thin and could become too weak if the metal were narrowed to make room for insulation.
Anyone who thinks the English are a reserved polite people has never seen one step on the surprise plug.
European travellers are generally impressed when I show them this trick, and sometimes rightly concerned that I'm sticking metal objects into a power outlet. If there's any chance the outlet is wired incorrectly, don't do this unless you can isolate the outlet or the key.
(Source: frequent socket replacements at a British university.)