I keep not finishing the first one.
I just really, really hate the corpse run bullshit. Every time I die, I'm forced to trek back to the exact spot I died before doing anything else, which is a stupid mechanic for a game that's about exploration and discovery.
I know it's a masterpiece and all, and I'm glad it's sucessful, but that mechanic just annoyed me too much, and I spend half the time just stewing over how much I hate that aspect. I realize after a few hours that the frustration over it, even if it's overblown, keeps me from enjoying the game.
I'm glad other people love it.