It's disappointing that this is downvoted when the Apple Watch is an obvious example that rectangular works and is winning.
When it comes to watches, I have to admit that I don't understand 99% of what is sold.
The Apple Watch design is probably horrible (at least I am ashamed of mine) but they get away with it because the design decisions are reasonable (bigger screen real estate) and the hardware and functionalities are ok. Battery is very limited but charges fast, etc
That’s called making the right trade offs and I think Apple especially has a very good track record of making the right trade offs in their products.