I guess I should start by stating that the community of Mount & Blade has been waiting for a pirate version for a long time. This game indeed fills that gap. I haven't played for a long time, but I played enough to know the basics of the game moderately. Here are some suggestions I have came up with to make this game even better.
-The boarding system seems to be kind of way too easy, I have never used chain shots whatsoever to board ships. The role of chain shots should be increased. It is also a pain to organize your fleet not to blindly crash into enemy ships (lost a couple of nice ships because of that). Ramming system could be introduced to naval combat.
-The system seems to revolve around one quest that kind of serves as a tutorial at first. I think tutorial and the quest should be separate.
-Town map. I think it would be cooler if we could wander freely in towns, the streets of Port Royal or Havana, just like in M&B: Warband. We should also be able to do bounty hunting, searching cities to find specific wanted criminals. All quests either ask you to trade goods or eliminate mob groups, which gets boring after a certain time.
-The naval warfare seems to be too blunt, it could be made more aesthetic (I personally loved the naval warfare in Pirates of the Burning Sea, not abilities wise, but texture wise). I believe some of us enjoy watching the details of their ships and the texture while they are firing cannons. The camera should also be improved. It should be able to go closer to the ship, like, it would be awesome if we could see the cannons as they are fired by gunners and etc.
These are all I could come up with. I hope they will be noticed ^_^