I've got one of these coming too. As Pike said it does look a bit worse/blurry, though that isn't the point; it's for the wider angle view and for a Quid, you can't go wrong.
*Edit.You'll see the effect more further away from objects (for the wider angle.) and closer up; (for the fish eye effect.) most people use them for the wider angle though.
Saw the jelly lenses in Tesco for 97p near the phone accessories.