A little bit of a skill issue, but it's wonky to control.
Beautiful to look at when the more challenging sections aren't bombarding you with flashes and movement. Half of the challenge being figuring out where Owlboy has been flung off to which usually leads in to a failure spiral. Thankfully there are plenty of checkpoints.
If there were segments to breath and explore I'd be forgiving.

I finished the game with all the extras, and it took me around 14 hours. I recommend it, but not for the €19.50 price tag. I got it on sale myself. Some issues almost made me leave a negative review. The game is nearly 10 years old, so yeah... Since I was able to finish it completely (all achievements and extra's) and did have fun I will recommend it.

TL;DR: Great graphics and lovely music. But it feels like the game wasn’t properly playtested—especially noticeable in the cannon mini-game. The difficulty mostly comes from clunky mechanics, knockbacks, and questionable level design.

Wall of text that may sound like a rant
So yeah, beautiful visuals and nice music. The story is entertaining, though at times I had no idea why it progressed the way it did.

Your main character can only fly and carry things or people with skills. It’s a unique control mechanic and mostly works well, but also leads to tedious moments. For example, one character has a fast-firing gun that’s too weak to be useful. Most enemies move in large, fast groups. Sometimes picking up things or people, wouldn't work as expected.

Anyway, I used the cannon guy instead. His wide-range shot is powerful, but has a long cooldown. He can one-shot many enemies, but missing means a long wait. And somehow, even with a wide blast radius, I missed a lot of shots. Which is weird, because another shot at the same angle and range would hit just fine.

Controls and level design often feel untested, especially in fast-paced sections. The cannon mini-game is a good example: confusing controls and fast navigation demands. Often, you’ll crash into a wall during a screen transition because the next section suddenly turns sharply—no way to see it coming. It’s all trial and error. The harder parts of the game rely on this kind of design. Otherwise, it’s quite easy.

Platforming is also weak. In the final level, flying is (sort of) disabled and you have to jump—but the jumping controls are inconsistent.