Soundtrack and overall atmosphere are nice, But artificially downgraded picture looks odd. Fonts become ugly and barely readable. And it turns some puzzles into pixel-hunting mess. "increase resolution" option would be a savior.
Mods can fix many game's flaws, yet mods installation is cumbersome (in-game links lead either to steam or klei forums requiring separate accounts registration).
Unoptimized, unfinished.
It feels like unfinished game with awkward stubs in place of proper game elements (enemy spawning, jumping, crafting, maps structure etc etc etc).