Would you ride an electric bike?

Consider a normal bike with an electric motor on it. When you pedal it, it has an alternator type device that charges the battery (it can be charged via outlet as well) and when you are tired or unable to pedal fast enough to you can accelerate with a handle throttle.

Incentive to pedal would be to save charge costs despite an approximately 2 hour use per charge. Ideally, you may never have to charge it if you pedal as much as much as you use the electric motor.

The point of this would be to provide a cleaner alternate transportation in an urban setting without the full physical labor of a bike. The maximum speed would be around that of a bike (20 mph) with a much faster acceleration. Would you use this? If not why not? Assume that the size and weight of the machine would be the same as that of an average bike and that is around 100 dollars US.