There are some great ideas there, but maybe not enough iteration during the design phase or something led to an incomplete implementation.
The game would actually work if the player could feel a real sense of progression, this would require some genius level designers that would be able to create challenges that would require the player designing ever more complex and interesting gadgets built upon knowledge from designing simpler ones and playing around with the tools available to him.
The concept was too smart for the devs that worked on it to pull it off, maybe limited hardware held it back, this needed a much more robust simulation of the game world.

I'll give an example, I made the simple raft with put a fan on each side, my idea was that I could turn one fan or the other and steer the boat that way or turn both and move forward, a very simple concept for a vehicle, but you are limited because you can only have either all engines on or all engines off, to steer the vehicle, you need the "steer" stick that magically turns things around, the same thing applies to the flying wings, do you see how limited the tools available to the player are?

It's a sandbox with faulty lego pieces.