Proabably worth it if you get on time to dig for the hot water (2h adjacent to the low tide). Otherwise, there are nicer beaches in the area. The beach looks like bombs exploded all over due to everyone digging everywhere.
You can take whole day, starting early morning and stopping for lunch in one of the villages to wait out the burning sun. Cycling around Hpa-An is nice, the paths go either along the road or inside/by the forest. Most of the time you'd be exposed to the sun so cover yourself and have water with you.