Moving from Sunless Sea to Darkest Dungeon is a really perfect gaming transition, in that I think DD and Sunless are so similar in what they want to accomplish, but DD just does it so so much better.
Both have rogue-like gameplay with incredible story/setting/presentation, but where the story/setting in Sunless are mostly presented in text, DD tells its story mostly through gameplay. Once you watch the intro video and know why you are back in the hamlet exploring the dungeons, almost everything after related to what is happening (how the exploring is going) is gameplay driven. Characters die because you got them killed, not because a quest finishes with said character dying, stuff like that.
DD is also another poster child for Kickstarter and Early Access. I did my review of DD back in June, and most of what is written is still true (bonus meta points for the comments discussion being about Sunless Sea), but even since that time DD is now a better game. Information is more clearly presented, the difficulty has been ironed out a little (still super hard), and there are now more dungeons and classes. In short, Early Access really did help to make DD better, and Kickstarter made the creation of the game possible in the first place.
Both EA and Kickstarter can be abused, whether its H1Z1 sitting in ‘early access’ status while the company behind it says its released, to Smed asking for money on Kickstarter for a game he is going to make regardless, but overall the platforms are a major plus for gaming, especially when gamers correctly wallet-vote.
If you played DD in the past, I strongly suggest giving it another spin. The core is still the same, but the edges are even smoother and the gameplay still a brutally fun time.