I still have burn scars on my knuckles from working at a bagel restaurant that used one of those when I was a teenager.

They still have plenty of issues. The ones I used never toast the bread well enough in one pass (because different types of bread require different time), so you have to wait in front of it and pass it multiple times. The controls are speed and power and it's not easy to calibrate perfectly but once you put your bread in it even if you can see it's burning you can't just take it out, it has to pass through the entire machine. I've also seen cases where the bread will get stuck inside or go down the slide to fast and end up on the floor. I will take traditional toaster over them every time.