There's a lot they could fix and improve with a remake or remix.
- weapon balance, spreading weapons out though the game.
- chalice dungeon balance and a better tie in with the story
- smoother story progress, not getting lost on where to go next
I'm playing the game through again right now, and it's undeniably brilliant, but it's not perfect.
This game is one of the games that I always bring up when people ask the question "what game did you bounce off at first, but you're glad you stuck with it".
It took me a few goes to get into it, but after abandoning trying to perfect the stealth run and just enjoying it for what it is I started to love it