Stumbled across my first one of these the other day. It's not obvious at all that you should leave it in - particularly when accustomed to the ubiquitous slide

Stumbled across my first one of these the other day. It's not obvious at all that you should leave it in - particularly when accustomed to the ubiquitous slide-in-and-out-fast kind. This one tried to lock my card in, but when I reflexively yanked on it to pull it out, somehow it lost contact with the chip or something. What followed was a stuck card in this machine, and the machine stuck on "verifying"... no cancel buttons worked either. Eventually, after a long and disconcerting minute had passed, it finally released my card and told me to go inside for payment. Definitely not user friendly in the slightest... and just an awful way to start your morning on your way to work.