At this point, Apple sticks to the idea of using a rectangular display in their smart watches. Needless to say that such a solution is better or worse than a round display. Rather, it is a matter of taste and habit.
However, a new patent suggests that Apple does not avoid the possibility of using and round shields. Both documents are called “electronic device equipped with a display with rounded edges.” In this case we have in mind is not curved screen, but on the round.
The document describes various technological nuances that are of little interest to most. Also in the documents there is no mention of the operating system, interface, or something like that, so that patents are only suggest that Apple is considering the possibility of creating such a device with a circular screen. And so it will come on the market or not, it now can not be found.