From a sort of academic standpoint, it really is the worst interface design ever. A primary tenet of interface development is creating "discoverability," - simply making things discoverable. A button is 100% discoverable. A menu item is perhaps 70% discoverable, because you have to go looking for it. This caps-lock thing is 0% discoverable. Numerically speaking, it's as bad as any design could ever be. That's pretty bad.