What is the disadvantage in having ducts in the ceiling?

One disadvantage of having ducts in the ceiling is that they can lead to uneven heating and cooling, as warm air tends to rise while cooler air settles lower, potentially creating hot or cold spots in the room. Additionally, ceiling ducts can be more challenging to clean and maintain, increasing the risk of dust and allergens accumulating. They may also require more complex installation, which can be more costly and time-consuming compared to traditional floor ducts.