Yes I have one. It's a Raleigh Modus, bought earlier this year. It has 7 gears, which you use like normal gears.
Ebikes are heavier than normal bikes.
You have to pedal all the time, just like a normal bike. You can choose no power, or one of the 4 power levels, to give you a boost. It's like someone giving you a push up a hill! The higher the power level, the more battery power it uses, but the faster it goes.
When you have the power switched on, the power will cut out above 15mph - this is a legal thing, for safety. You just keep pedalling as fast as you like, it's just that you won't get any extra help from having the power on, until you drop below 15mph again. There's a display unit on the handle bars which gives you all the info you need (like a fitness tracker).
The batteries we have (also heavy!) last for up to about 90 miles. In practice, you won't be using the battery power for your whole trip, either through choice or because you are going at over 15mph. The battery comes with a charger which plugs into a normal mains socket.
The weight of the bike varies between makes, and the balance depends on where they have placed the battery and the motor. DH did all the research and picked these ones because the weight is in the middle and relatively low down. On some makes, the battery is on a rack above the back wheel, which I imagine affects the balance.
We 'test drove' them from a national chain before we bought ours, mainly because it was a significant outlay.