I've ridden 100 miles in the last week and other than a sore butt, I'm really enjoying it.
I researched a number of e-bikes, and settled on an "Aurora" from Evelo (E-velo, if you will); they only make e-bikes. They're a Seattle/NY company.
About an hour or so later, it's beginning to look like a bike:
Here it is outside, and finished (and a little dirty, after a rainy ride):
You can see the motor next to the pedal; the battery is where the rear fender normally would be.
It's intended as a "pedal assist" bike; you select any of 6 levels of assist from 0 (pure pedal power --- a standard bike) to 5 (lots of help from the motor). The pedals don't turn by the motor --- you control them with your legs, as with any normal bike. But both you and the motor contribute to drive the chain and (through the transmission) the wheel.
Transmission? Yes. The bike has a NuVinci continuously variable transmission (CVT) that you shift by twisting a grip; no gears, no derailleur, no fuss. You also can shift while the bike is stationary, or in motion without pausing pedaling. With no fixed gears, you have (in effect) infinite adjustments available between high and low settings.
The bike also has front and rear disc brakes, front-wheel suspension, a front fender, and LED head and taillights.
There's a twist-throttle on the left handlebar. If you want, you can use the bike as an electric scooter (no pedaling), but that kills the range, and seems to defeat the purpose of having a bike. I like the electric boost when starting at stop lights in city traffic: it gets me going fast so I don't end up as someone's hood ornament (it's a heavy bike, what with the motor, battery and heavy-duty frame); once through the intersection, I then I switch to one of the pedal modes.
The control layout is very different from the motorcycle style I'm used to: here, throttle and front brake are on the left; shift and rear brake on the right. But it's been long enough since I've ridden that old habits rarely interfere. And I'm glad for my motorcycle experience, because it makes riding in dense traffic a bit less foreign.
(Still, being a relative tortoise among Boston hares is, um, interesting.)
Here's the control panel; I also added a smartphone holder, so I can use it for GPS navigating. (The control panel has a USB port so you can power a smartphone from the bike's main battery, if you need or want to.)
The control panel shows charge state (100% here); odometer/trip meter (then showing 43 miles/69km; you can switch between metric and Imperial measure); speedometer, PAS (pedal assist) mode, and how many watts you're currently using.
I got the standard 250w motor (which can roughly double to 500w under brief heavy loads). The bike comes with a 36v/10ah Li-Ion battery; I also bought a spare battery to carry with me. (There's also 500w option, with bigger batteries.)
Evelo claims 20-60 miles on a charge and, and that seems reasonably accurate. The 20-ish miles (32km) would be with lots of starts/stops, hills, high-speeds, or otherwise relying heavily on the battery; the 60 mile range (96km) would be on mostly flat ground, at modest speed, with lots of leg power.
You won't be stranded if you misjudge power consumption. Set the CVT to a low gear, and you can grind your way home same as with any bike.
But I'm keeping it.
I've done some long rides, like this 30-something mile loop (50ish km), to and along the Minuteman Bikeway, a former rail-bed converted to a trail (https://en.wikipedia.org/wiki/Minuteman_Bikeway):
The museum car at the Bedford terminus of the trail; you can see the trail to the right):
A 27 mi/43km loop, including some of the Charles River Bike Path:
A rainy 10 mile (16km) ride to Mystic Lakes, where I'm a volunteer in tracking the annual herring migration:
Lunchtime rides along the Mystic:
Yes, my butt hurts. But so far, it's been fun. :)
Bike info, fyi: http://www.evelo.com/
(The second hundred miles, here.)