And gentle exercise is what you'd get with a motor power through the gears arrangement like the Gazelle Easy Glider has. Other bikes with this sort of design include the original Giant Twist Lite and Comfort range (only avail second hand these days), Swiss Flyers or even if you feel like spending well over £2000, the Swizzbee.
The advantage of a motor power through the gears system is that (just like in a car or motorbike), the design enables the motor to keep running at its optimum efficient speed even when the bike slows down going up hills. Hub motor powered bikes (such as the current Giant Twist, the whole eZee range and many others) on the other hand have the motor running either directly connected to the wheel or via a single fixed 'compromise' gear ratio. This means that (just like with the car/motorbike stuck in an intermediate gear example) when you get to steep hills they often slow to a crawl or even stop, at best the motor becomes less efficient and binges on battery power.
I have a Giant Twist Comfort and its great for climbing steep hills (even 1 in 5 ones which are far from a blip on the landscape). I also use it often for carrying shopping in my panniers on the back. According to AtoB magazines review of the Gazelle, it has much in common with my Twist. The Gazelle Easy Glider was rated very highly in their recent review.