First and foremost, I was turned onto this series due to the YouTuber Mother's Basement where he mentions this as one of his top romance picks. Well, I'm here to tell him he's completely wrong. The romance in this series is basically non-existent. So, if you're thinking of this series for the same reason - don't. Just don't.
So, now that we've pretty firmly established this is not a romance series, how is it as a sports anime? It is completely and utterly... adequate. My entire impression of this series is that "it's okay". But let's break it down:
At heart, this is a series very similar to something like Days! or Welcome to the Ballroom where the viewer is meant to have minimal knowledge of the sport and we learn the sport as the protagonist does. They learn, they grow, and we are introduced to progressively more advanced information as the series progresses.
The problem here is that, as mentioned, this story is just adequate. It's a very obvious plot, with no real twists and the climaxes are all very obvious. My biggest issue here is the pacing. It's very slow. The matches are slow, the time between matches is slow, and the romance is basically at a snail's pace.
This is probably where the series lacks the most. The characters are all drawn fairly poorly and there are times where I've actually paused just to kind of marvel at how badly drawn the faces are. The action sequences are better but unlike a series like Haikyuu, you don't get a good feel for the movement and instead we are presented with a lot of still images of "motion in progress".
Again, it's very adequate. Voices are decent and there's no screaming or yelling. The whole series has kind of a softly excited feeling to it. Characters are generally subdued and it's actually kind of a nice reprieve considering some of the louder series we've seen lately (lookin' at you Black Clover!). The only sound they really miss on is the sound of the ball hitting the racket. They give it a weird kind of popping sound where it should sound more like a metallic spring.
The characters that the directors cared about are all fleshed out fairly well. Though why they chose not to care about the love interest is beyond me. What holds back the series is the few very odd characters. Like the rival, in the first few episodes, is just a brooding and angry teenager for... no reason. They never explain his brooding, and we're just kind of supposed to go "oh, it's just part of his character, sure". And what makes this even more painful is they even introduce a love rival. Like, why introduce a love rival if you don't even flesh out the main love interest?
But, the series focuses on the protagonist and they spend 90% of the time on him. He's a bit obsessive but is well adjusted. They try very hard to make him a humble prodigy (sort of) and it works mostly. He's likeable, which is very good since he's basically all we've got.
I'd say this series is for people who like slow growth sports series with flat climaxes. I enjoyed my time watching and I don't regret it but I didn't walk away with anything other than a feeling of "meh".