Robin Johnson is one of the best IF authors of the last few years, putting out games like Detectiveland and Zeppelin Adventure. These games, and Pirateship, use a parser-hybrid engine based off of Johnson's Versificator parser (used in games like the Xylophoniad).
This game doesn't reach the heights that Detectiveland did (which had 4 separate cases to work on), but it's a solid entry that will please fans of his previous games, and of puzzles in general.
You play as a pirate on an island that has a surprising number of inhabitants. There is a lot of conversation, and several complex mechanics (including a diving apparatus and a kind of pirate prosthetics lab). I used a walkthrough for a few of the trickier puzzles.
This game is polished, descriptive, has good interactivity, and I would definitely replay. It didn't draw me in emotionally, as I didn't really feel any kind of connection to the NPCs, or find an overarching story like Zeppelin Adventure. But this isn't a game looking to be deep; it's looking to entertain, and its succeeding. I debated on whether to give a 4 or a 5, but the primary purpose of my ratings on IFDB is to indicate the quality of a game compared to all other IF, and so I think a 5 is appropriate here. Compared to Johnson's other games alone, I would give this a 4.