Let me start by saying this expansion is compatible with all the Descent expansions EXCEPT Road to Legend (known as RtL from here on out).
Though you do have the option to pull some cards from RtL and play them in this one.
This game is great, it has its flaws, but they really did try to do a lot with it.
i like the idea that you are at sea, having to travel around to islands, and working that way, some of my friends do not like this as it "does not fit in with the Descent Universe" that they have been playing. This is true, it has moved away a little bit, but who is to say there isn't pirates in this universe?
The reason why I gave it 3 stars is some of the gameplay elements just do not work as well as they should. Ship battles are fun, but ship movement is leaves a lot to be desired.
If you are looking for a campaign expansion to Descent, I would recommend RtL first, but these are becoming harder to find. Secondly I would recommend this expansion if you have all the others and have beaten RtL, or you just want a new way to go.
Word of warning though, put down the extra 10 bucks to purchase the cardboard map. The map that this comes with was very disappointing, especially being a FF game.