I used RIBShine
with great success on a very old and dirty Humber I used to have (which was army grey). It made it look like new again.
I have heard that it can cause streaking, especially on darker hypalon. but i think this is when you try to apply it in direct sunlight and drips of the Ribshine dry as it runs down the tube.
This topic has been discussed many times - use the forum search and you will find loads of info.
I now have a new boat and I am currently using Armour All on it (as suggested by Manos I believe) as this tends to protect the boat from getting dirty in the first place and is also supposed to have UV protection qualities.