There are two basic categories of electric bike, and their uses don't offer equal crossover value. The first category is essentially a normal bicycle that has been outfitted with an electric motor. These bikes are the same size as a standard bicycle, and handle almost identically, save for the obvious benefit of added motive power thanks to a motor and battery.
There are individuals who claim to have lost considerable amounts of weight by using an electric bike. A recent prospective cohort study however found that people using e-bikes have a higher BMI. By making the biking terrain less of an issue, people who wouldn't otherwise consider biking can use the electric assistance when needed and otherwise pedal as they are able. This means people of lower fitness levels or who haven't cycled in many years can start enjoying the many health benefits E-bikes have to offer.