Yes, yes and yes, although you need to watch the battery life. Clearly not aimed at the "serious" cyclist, but good fun, takes about 50% out of the pain of going up steep hills. I use one for cycling to and from the station each morning and it allows me to have some exercise without arriving at the station in a sweat - which is my main priority when subsequently sitting on a train for an hour.
I did the approx 40 miles along the South Downs way out of Brighton via Falmer through to Alfriston during the summer on a Wisper 905. It (and I!) did start to struggle going up the Southease hill but it made for an enjoyable day. It's used daily for going to work and I reckon it saves me around £50-£60 in fuel a month. I wouldn't say I'm overly fit compared to some but it's more satisfying than finding a car parking space, just wish the batteries were not so expensive!