No permanent modifications to your precious kayak are required, so have no fears about drilling holes through your deck. We found the sail light and easy to control. Turn your paddle to the left, the boat goes to the left. A leash is provided to help ensure your paddle stays with the boat. Merely pushing your paddle forward lowers the sail to the deck.
Kayak sailing is primarily a downwind experience.
So remember, if you get a nice blow in one direction, you've got a headwind to deal with on the way back. That fact became important for us when the wind picked up, and the small islands in the distance all of a sudden loomed large. Had we actually wanted to go in that direction, this wouldn't have been a problem. Practice is required to avoid swimming, but at least in the event of a capsize, the colourful sail would be highly visible, assuming someone is looking for you. We really enjoyed it.