Whoa, this is a surprise to me. When was that announced? Is it gonna be translated?
I used to play Uncharted Waters 1, then 2 on SNES all the time. Very open-ended game, you had a fleet of ships, could buy/upgrade ships, raid other countries' ships, discover and map out new territory, hang out with the natives, do some trading... There were a fuckton of characters, each with a specific scenario. Well, it was a great game.
It's a lot like "Pirates", yes, very time-consuming. If you like open-ended games like elite, pirates, or morrowind, this is the kind of game without rails you should get.
Well, if it is a good sequel, of course.