Rincon is going to be a handful if you not an experienced surfer. I have not surfed the break but heard it can be big and fast. With the reef, it makes bailing a lot more dangerous. But, it is the best surf on the island. I did surf a sand/beach break on the NE coast in the town of La Selva. The surf shop only had a few boards to rent and no one really spoke english. The break has a real urban feel as the town is concrete and run down, but the beach areas are along the moutains, so there is a cool contrast. It was easy to get to an friendly. There are some breaks near Old San Jaun.
Here is a good map/link to check out stuff. I surfed there in Feb in shorts. The water was wonderful. Puerto Rico,Puerto Rico surf,Puerto Rico surfing, WannaSurf, surf spots atlas, surfing photos, maps, GPS location
Defeinetly get out in the water, be safe. The locals were cool to me. Part of it was that I knew what I was doing and respected there waves, etc. Good Luck!