It is so down to earth, close to the real life of any growing kid. Situation every teenager go through, thoughts, desperations, love, etc etc.
What shown is exactly all situation a kid faces, a family with a kid faces. Also ever episode is unique, have something different to say.
And ofcrse, it is about the childhood and whe in memories, each one of us would remember the most is the childhood. So it attaches very emotionally.