Motorized Arm Bike vs Manual Arm Bike

Has anyone used either of these? I'm shopping for one, just don't know the benefits of having a motorized one as opposed to the manual.

The manual arm bike I had wasn't very good. It was one of those $9.95 ones and it was difficult to get any kind of smooth pedaling motion. I felt like my arms were lurching more than pedaling. I prefer the motorized one that I have, even though I don't use the motor; it seems to be better quality than the manual one and has a much smoother pedaling action. I don't switch on the motor because I want a more aerobic workout. Kix

I can't figure out what the motor does for you?

The motor makes it easier for you to pedal if you aren't in good shape. It assists you with pedaling. Kix