Yea, the art is great and along with the text really helps build the world. I have rarely seen an rpgs rules support the setting so well.
DIE was great. I haven't read it, but I have played it. I feel hesitant recommending it because the experience seems heavily variable depending on GM, but it was definitely one of my personal favorites.
ETA: pg 10-11 of the wildsea book has a layer breakdown of the sea and it's my favorite part of the whole book. Maybe I'm just a sucker for any science textbook adjacent art, but it does such a great job of immersing you (imho). I think they should make posters of it and have it a bit more prominent in their marketing, but it's possible I'm off base. I feel like you can use interesting races in lots of different settings, but the sea is so integral to the game, it should be one of the big draws for players.