I tested the Sduro 8.0 towards the end of last year (there's a new range out for 2018) and was surprised by its nimbleness. You expect e-bikes to be less maneuverable than their acoustic predecessors, but, pelting down some bespoke forest paths near Pedal & Spoke in the Surrey hills, I found I completely forgot that there was a box of electronic EPO on my frame. Partly, that's because the battery is cleverly integrated into the frame to decrease drag; mostly, it's because the suspension is soft and the steering nimble, much like a normal mountain bike.
While the first functional battery was developed in the year 1800 by Italian physicist Alessandro Volta, a practical battery would not be seen for several decades yet. By the end of the 19th century, practical and portable batteries were more widely available, this finally freeing the electric motor to be used in a wide new array of applications. It might come as a surprise, but the electric motor, battery, and a bicycle were first paired as far back as the 1890s. It would be approximately 100 years later that electric bicycle development finally entered the mainstream, but the technology and concept behind the electric bike were all in place generations ago.
The way they work is pretty simple: The motor kicks in with extra assist when you pedal, and there are different levels of assistance. That's it. Just turn it on, pedal, and go! You can also turn the assist mode off and ride it like a regular bike. And e-bikes stop assisting at a certain speed (in the U.S., it's 20 mph or 28 mph depending on class) for safety, of course.
Because e-bikes are capable of greater speeds for longer periods of time than standard bikes, you want extra control. Wider tires provide traction and some bump absorption with little penalty. You also want strong brakes to slow you (and all that extra weight) easily. It's worth looking at the quality of the brakes and investing in bikes with better ones if you can.