Very smart in deed, as someone mentioned it cannot be that hard to make one yourself (famous last words)
I must admit I find cutting dovetails by hand as quick as any method, so I'll stick to that - especially at that price, but it does look very very clever and very simple to use
When I first saw this, I thought it was an April Fool's joke. It now seems very real and to have a lot of potential for some folk. I can imagine it being a boon to box makers for example.
I think if you don't already have a full set of tools, then this could be a very good option. Especially for someone who doesn't want the noise of a powered saw but the convenience.