Whether Starbucks' almond cakes are sweet or not depends mainly on personal taste. The sweetness of almond cake can be controlled by adjusting the proportion of sugar. Some almond cakes may be sweeter than others, but the sweetness of most almond cakes is acceptable.
However, because Starbucks almond cakes are sold as desserts, their sweetness may be higher than ordinary almond cakes. If you don't like food that is too sweet, you may need to pay attention to your choice.
Generally speaking, Starbucks' heart-shaped almond cakes may be sweet, but there may be other flavors to choose from. I suggest you check the product details before buying, or try other Starbucks desserts to determine whether you like sweets.