There are exactly 2 spots in Oceanhorn that are odd difficulty spikes: a lever/moving platform puzzle which difficulty to pull off reliably puts it miles away from any other in the game, and a shoehorned game-ending usable item that's dropped in front of you just before the first stage of the final boss, and is meant to be used at a precise moment during the second phase, ending the boss and the game.

Everything else is pretty much where you expect it to be, the optional items are indeed optional, the random drops by jars or enemies match what you currently need (you'll find more heart when you are hurt, mana potion when you've used spells, bombs and arrows after you've used some of your inventory), and the world map is small enough with a displayed completion level for each location that enables to quickly identify the next steps of your journey and/or the locations to revisit later.