I like it.
It's good for long distances.
I like even better that half of the expenses can be refunded by the army chest.
I think "turning back", and "disembarking on the nearest shore" should be implemented in a not so far future, because sometimes we mess up calculations or miss a turn or 4, or misclick.
I like that we can't see other people at sea with us - makes it harder to coordinate an assault. But I do hope that the turn in which attacking troops click the "disembark" button, the defenders in a region get a warning of approaching ships. This way, at least people 1 region away can try to arrive there and mount a defense. Or maybe you get the option eventually to build a lighthouse in some regions, that will give you a warning of ships that get 3-4 hours close, or will just disembark at next turn.
From my sea experience, you can easily see islands 10 sailing hours away, if they have tall enough mountains, and 50' ships about 2-3 sailing hours away, if you're some 20 meters above sea level. Touristic cruisers you can see from as far as 6 sailing hours away, even at sea level. I guess I could go look up a map and try to find the distances I'm mentioning. It's all from sailing and observing from a particular beach. I'm not sure those medieval ships were as fast as the one I used, but who knows?
Who knows if it'll be even necessary, actually.
