Hachigatsu no Cinderella Nine lives somewhere in the intersection of three common anime tropes.
1. The "Sports anime" trope. Including, but not limited to (A) the character that used to play the sport but doesn't play anymore, no matter how much you ask her to join your club (Suzuki), (B) the character that takes the sport too darn seriously while everyone else just kind of wants to play and have fun (Nozaki) and of course (C) the hyper-optimistic team leader who spends most of the show trying to keep everyone together (Shinonome)
2. The "Starting a new club in school" trope. Including but not limited to (A) fighting with the school council over creating a club, (B) struggling to get new members and (C) long explanations about technical subjects related to the club (in HnCN's case, mostly about Baseball equipment and technique).
3. The "Cute Girls Doing Cute Things" trope. Which is self-explanatory.
While HnCN won't defy any of its trope's conventions, the series does a good job of playing to each trope's strengths. Meaning that yes, if you enjoy all three of these tropes, HnCN might just be the show for you. However if you're looking for any sort of depth here, if you're looking for unique, distinguishable characters, if you're looking for well thought out dialogue, or if you're looking for something, anything else beyond the youthful optimism of cute bat-swinging 2D girls, then you're better off looking for another show to watch.
Here's where the technical qualities of the show come into play. Certain shows that play to their tropes distinguish themselves from the pack with good background art and fluid animation. In HnCN however, beyond the character designs (which are decent-to-good), the art quality makes this a difficult watch as the background art is simple and repetitive, the animation lacks fluidity and the character's faces are oftenly off-model.
Overall, I find this show to be quite enjoyable: I like the three tropes I described earlier, so I'm naturally inclined to score this higher than it "objectively" deserves, and I can honestly see some people actually enjoying this. With that being said, the poor art quality, the lack of depth in dialogue and character building and the mostly unoriginal story will turn-off a lot of people, especially those who aren't interested in the three-trope intersection previously described.