Great utility
I was using other tennis score watch apps but found this one promising. If two things can be considered to add to the next release, it will be the app I stick to.
First there is some slight delay after the click before score changes. It is slight but enough to get you take a second look to make sure it clicked.
The second thing is that I wish it anounces the score via the watch speaker. It serves two purposes: I can repeat and announce it to my opponent, and it reassures that I clicked it.