TrueAchievements has their review up:
https://www.trueachievements.com/n31991/sea-of-thieves-review
Since its reveal, the concern we've been hearing about
Sea of Thieves has been its apparent lack of structure or content. The game looks beautiful and charmingly lighthearted, but "what do you actually
do?" The question was one Rare couldn't shake leading all the way up to release, and to the credit of those wondering, it seemed to be a fair question. The answer, as it turns out, is a whole lot, thanks to memorable player-driven storytelling where any voyage could be your shining achievement, but the tabula rasa approach won't be for everyone.
...
Sea of Thieves can be a low floor, high ceiling experience. The wrong crew is the quickest way to find boredom before treasures. Sharing seas with griefers can be rage-inducing too, but in both instances, you're always able to quit out and try your luck again with new players. Of course, it's played best with a solid team of you and three friends, but provided you bring a willingness to fill in the gaps with your own role-playing or shenanigans,
Sea of Thieves is a charming and gorgeous title no matter the team size brimming with emergent stories that the relatively basic outline provides. Play it long enough and it's impossible to not come away with your own tales to tell.
Sea of Thieves is all journey with no real destination, but if that doesn't immediately turn you away, it'll be a pirates life for you.