I've also seen them, they're also in places such as rice lane and along the dock road near the tobacco warehouse. I think they will look good as long as they are regularly replaced/cleaned, which they more than likely won't be.
Regarding the rocket junction I think it looks absoloutely brilliant and gives Liverpool a truly international feel. I would like to see something similair done to other monstrosities across the city such as the bootle flyover and the dale street flyover. I wouldn't expect anything on the scale of the rocket, but it would be nice to see them at least cleaned and given a fresh coat of paint.