I finished this tonight. Loved it, most of all because of its echoes of The Witness and Outer Wilds with their freedom to engage directly with the experience without the mediation of dissonant "this is how the game works" instruction. Comparisons to Dark Souls are not that useful - they share a few mechanics and elements but they the reasons for their greatness is quite different imo, and this probably shows how increasingly redundant the "Soulslike" genre descriptor has become. Some of the combat and boss design in particular lacks tightness and fairness, but not to the extent that it dampens the overall mood and thematic content of the game as a whole. I found it interesting how finding your way through Tunic very much relies on already understanding some of the key grammar of games, but then also deliberately subverted or commented on this in various ways.
I've not played a 2D Zelda all the way through except Minish Cap. Should I go back and play them if I enjoyed this? Or are they more about the combat and puzzling than the narrative and themes?