I think Zero Chill is a great show with enough drama to keep the target audience (kids/young teens) interested.
Though I am out of the intended audience bracket, I was engaged enough to watch the whole series, in the company of younger family members. The acting of the main cast was surprisingly quite subtle and touching in moments, which was nice to see - especially in moments where other kid/teen series have fallen flat or been overdone. I really enjoyed the performances of Ava, Jacob, Bear, and Mac.
The series was also able to show tension without the threat of physical violence and though my adult brain did cringe at certain moments, as a kid I would have loved the humour.
Overall, I think it's unfair for 45-year-old adults to rate a show negatively when they are clearly not the target audience. You have to remember, the characters are 15 YEARS OLD - at that age, everything feels like the end of the world. So I think it was completely valid for (i.e) Mac to be angry about balloons...