A lot of work clearly went into the aesthetic and programming. The music is really relaxing and what I'd expect to hear for a game like this. The rubber duck is cute and I love the water patterns. All the collisions are pretty spot-on and polished. Unfortunately, it trips a little bit at the finish line. Left/right being flipped when upside down is a bit disorienting, and it would be nice if there was a button to automatically flip when the camera changes. I'm also not sure if the camera going underwater fits super well as a new perspective, but you adhered to the colors really well in a way that makes the palette seem bigger than it is. So it's definitely thematic overall.
Overall, pretty good stuff in need of minor additions at most. I can't think of many games with a rubber duck as the main character, so you get points for originality!