I believe that the game is complete enough to be worth the money, the rest of the game will most likely be minor changes and a couple new biomes/bosses to top off the 6 already in the game. It doesn't feel too short or bug-ridden like an early access game, it feels complete enough.

My first playthrough was 70 hours, my second was 50 hours. I have played it a lot more since then, and if you use mods that add quality of life or new content to expand upon the already existing game then you can easily find yourself at 500+ hours of gameplay.