There's one thing for certain about this, the graphics are amazing. You control a boat which stays in the middle of the screen which scrolls in eight directions, revealing a little more of the landscape as you move.
The object is to manouevre the boat so that you finish a course within a time limit. If you manage this, you repeat the process with a shorter time limit and more obstacles. There isn't any flicker and the detail of the objects on the banks is incredible.
The sound effects are good too. However, the playability lets it down badly. Even though the graphics are probably the best I've seen on the Beeb, the basic concept boils down to moving left and right and avoiding obstacles. There's only one type of course and the general scenery is the same every time. Once you've seen the whole course - which doesn't take long - there's no incentive to go back to it.
Maybe some people would like to buy it just to see the graphics but for the rest, Jet Boat can't be recommended.