What I love is you have to carefully watch the screen to pull the card out when it's done, otherwise it starts a really harsh a beep that's designed to prevent you from forgetting your card, but is just flat out obnoxious if you haven't.
I feel awkward and foolish with it, since it's ostensibly so simple, but so inconsistent. Add in a watching-water-boil time delay, and it's just a great recipe for social anxiety. One wrong move can jam the works. (Like, I once pulled the card out too early when I heard it beep at a Target and the register had to cancel the order and restart.)