I'm honestly mixed on the DLC. On one hand it's more Wartales, which is obviously a good thing. On another, that more Wartales is hopelessly diluted (quite literally) by a grand body of water that does nothing but increase travel times inbetween where you are and where you need to be. Added together all of the islands of the archipelago would just amount to a single region in the main game. It's just padding for the sake of padding, as nothing much of note happens at sea. Even taking combat encounters as an example, you can just easily sail past pirates and other hostile ships. They barely react even if you're point blank in their face. Next to that we have occasional floating loot... who cares? And two additional fishing mini-games... again, who cares? By the point you get to it food is not going to be a problem. Even if I do think that fishing is much more relevant in Belerion than in the main game, so it's at least something.
Then there's the Lords of the Seas ranking board (ohai One Piece!). The most important reward for defeating said lords is the blueprints which all seem to converge on making sailing by ship faster. This makes it functionally useless as by the time you're around to tracking all of these blueprints down you'll have long since been done with everything Belerion has to offer. Even the new seafood oriented dishes are hardly worth it, as all they do is give sea related or reputation bonuses. It's also very much useless to have them a la carte in your tavern, as only pirates and sailors eat them, and the feasts almost never sell for much and don't seem to participate in the supplier economy. So even as an addition to your tavern it's a clear disappointment.
Like honestly, I don't get it. The rest of the game synergizes perfectly with itself. There's systems upon systems that work in tandem and build upon one another. You can have a zombie survivor mini-game in the same breath as a rugby clone all using the same battle system. And it works. It works like a g0dd4mn charm. Not here though, they added an entirely new system based around sailing that is used exclusively here and nowhere else, and it just adds tedium and frustration to an otherwise perfect game. Honestly, it's not even borderline gimmicky, it's just a plain gimmick that Wartales doesn't need.
I'll give it a thumbs down. If you can't get enough of the main game and are thirsting for more after finishing, sure then, get it on sale. What's on the islands is still just as good as the main game. Otherwise just stay away, it's really not worth it as this sea has the width of an actual sea, but the depth of a puddle.