A blast (if used on UK roads) partly because it has an illegal 500w nominal motor.
We just moved from a Viking tandem with Woosh conversion (XF07) to an 2nd hand Ecosmo.
The Ecosmo tandem bike is a fun and practical 2-seater bike that is ideal for riding with a spouse or a friend. Have some fun with this electric tandem bike.
ecosmobike.com
The change was mainly because the Ecosmo is easier to step over; I was finding the Viking increasingly difficult. Also, the Ecosmo folds so is much easier for transport. These are both rated 250w, so legal but almost certainly not so blasty as yours.
The Ecosmo is looking good so far with some changes. I needed a slightly higher seat post for me; I'm around 5'10" (maybe a little less now!) We also swapped over the stoker post and saddle for the Suntour NX12 we had on the Woosh. The top gear is very low, about 50". I'm considering changing the 14-28 freewheel to an 11-28 or 11-32 which will take it to around 60-65". We also moved across our two sonorous bells.
When we have finished tinkering and ridden for a few hundred miles I'll post a bit of a review.
Our tandem rides are mainly fairly short and not very fast. I wouldn't suggest either the Viking or the Ecosmo for longer distances.
Most other foldable (transportable) tandems are in a much higher price bracket; I can't give any first hand opinion on them.