Since this has ended, I'll give my 2c on it.
It had a very strong start. It was really enjoyable in a slice of life kind of way. The art was good too and I liked that mc wasn't an "average guy with average grades and average athletic ability". He's good looking and pretty smart. The heroine's character design is also really good. However, it started to take a turn when Iris came in. She's just a very unnecessary character who subtracted value from the existing group dynamic. She got a lot of focus despite being such an annoyance and the last few chapters ended up focusing on her. Then the author had the nerve to bait us with a possible confession/confession-response.
It would have been so simple to give a satisfying ending where the mc and his senpai end up dating. The last few chapters could have been spent on the build up. This would have tied the story up nicely, given that the whole manga started because the mc confessed and joined the (unofficial) club. Why do some authors do this? It just makes your reputation suffer and pisses off the readers. Who benefits from this?
Overall, worth a read, but the ending and the chapters leading up to it are trash.