This is my second purchase (the first one was borrowed permanently!) Great for rubbing out those fine errors tucked between the bits I want to keep. The trick is to let the motor do the work and not press down for the best results.
I didn't know how much I needed an electric eraser until I got this one. I love how it takes off coloured pencil. I found it a little bulky in the hand, but I got used to it fairly quickly. If this one suddenly vanished, I would absolutely buy another.