Yes you can still use it as a pedal bike but it is a little more dificult. You are turning alot more parts and have added weight to the bicycle. I have a single speed which I think makes it alot harder, with a multi-speed it should be much easier.
I still like to shut the motor off and pedal sometimes but only on flat land or going down hill. But like I said I have a single speed and never have gone up a hill with motor off. Somebody who rides alot and is in good shape should have no problem just using the pedal's.