TLDR: You will enjoy this game if you are fan of exploring, great discoveries era and wales

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Minor Spoilers ahead.
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You are a guy who wants to kill Moby ♥♥♥♥. In order to do that, you need to hire a crew, gather money to buy resources and ships, have countless of adventures until you trace the big white and have the power to put a bullet in his eye.
Leveling:
You can be a Hunter ( which will further specialize in Harpooner - hunting whales or a Fighter - fighting pirates and other enemies), Sailor ( various sailing bonuses and some skills helpful to prevent larger whales from capsizing your boats for example) Craftsman ( cook and can also reroll dices) and Scientist which is the defacto healer.
Furthermore, every man of your crew can have any of the jobs above, and you can also hire cabin boys which doesn't cost resources and can be promoted in any way you want, but it takes longer to level up.

Game Loop
You buy resources and hire your crew and then you travel the world between various ports, hunt whales, kill pirates, avoid various natural hazards, do quests, sell the blubber, oil and whale meat for a profit, rinse and repeat until you advance through the story long enough and have enough resources to take down Dicky Moe! You have various whale types to hunt, with different skills, drops, hunting locations and migration patterns. You also have a morale system and other small neat features, which most of the time not game changeing, they are fun and can be used for some variety in game.
Ships
You can improve your ship with various upgrades and also buy bigger ships with more whaling boats.
One problem i see here is that your crew needs to have certain skills in order to buy a bigger ship and you having limited crew space means you need to fire men and hire other man in order to buy the ship. That is frustrating especially if you raised a cabin boy and now you need to fire it because it doesn't have the needed skills.
Difficulty and Role Play
In the beginning and until you understand the mechanics the game can be hard and unforgiving. After you buy your second ship, which has 2 boats, therefore more firepower and a bigger hold you will start to make a big profit and the game starts being too easy ( like many games do). The trick here might be to roleplay a bit and make it harder. You can hire a weaker crew, stop farming whales and just hunt if you encounter one, choose weaker skills and roles. I am doing this in my current playthrough and it's loads of fun, feels quite realistic, always wondering if you will have enough money to buy food or if the next encounter will be your last.
That doesn't mean danger is not present at every step, fighting enemies is dice based, so there is a big amount a chance involve. One tale smack from a bigger whale while you had bad dice rolls and your game can be , well, game over.
The final boss, Moby ♥♥♥♥, or Dicky Moe how i like to call it , Tom and Jerry reference :P is quite a lot more difficult than normal whales, but with a bit of researching and strategy you can take it down.

Like i said in the TLDR, game is fun and you can easily sink 50-100 hours into it. Have fun!