The more I wear my Apple Watch, the better I understand it's rectangular shape. Sure, it' reads easier, but the design enhances the shape of our arms. The wrist is round, but the arm is long (rectangular) and flat which is why a rectangular watch looks much nicer on someone who wears short sleeve shirts - sure, the round is nice and it's a personal choice in the end, but the rectangular matches our body shape. Pebble looks like a toy and there is nothing professional or flattering about it. Usefulness; perhaps so.. Style and usefulness is why apple is selling so many watches.