I’m a big tennis fan and also read quite a bit of fantasy and litrpg. I was definitely onboard for the premise because at least the storyline was a novel concept. Overall execution was fine. It’s more like YA litrpg and so you’ll have to limit your expectations in terms of character depth, etc, which was lacking.
The main problem for me was just that I’m not convinced the author is actually a tennis player as opposed to someone who tried to research tennis for a book. There was a ton of little things that they got wrong. Small example of many, no one says “love all” at the beginning of a game. I’ve never heard that in 15 years of playing, but apparently every character says it all the time.
The idea that this Peter guy is a high school student who happens to be the best player in the state and is some kind of super prodigy, but decides to drop everything to teach a complete beginner in all of his spare time is also kind of stretching credulity.
Even still, it was harmless, and again the story was novel enough to make me want to finish it.