I purchased the Heybike Racemax Electric Bicycles: 27.5" E-Mountain Bike, 500W Motor, 48V 12.5AH Battery, Front Suspension Ebike in May.
The bike works great. Motor has great power up to around 20 mph, and appears to be good for around 40 miles, although I've only ridden it around 25 at any one time. Definitely adequate power, even uphill, and I weigh 240lb.
The fit is decent for me at 6ft. tall. I'd prefer it if the handle bars could adjust higher. There is plenty of range in the seat. I set my seat height like a cyclist, so maybe higher than most others might. If you sit lower, the max handlebar height is probably enough.
Cons: the component set (gears, brakes) is obviously entry level. That is exactly what one should expect at this price point, but it should be noted. Its difficult to get the brakes adjusted without some kind of squeek, another entry level problem.
The pedal assist is not sophisticated. You can set it at 0, or you are e-biking with ghost pedaling or the thumb throttle. It isn't really subtle enough to just "help" when riding.
In sum, it is an inexpensive way for me to get around town during the summer, and I have used it non stop, putting several hundred miles on it. I definitely recommend at this price point.