Depends on the perspective, I guess. I was working in several different places, and sometimes I had hard time. Even working in the worst places, I felt better than in school.
I hated elementary school, because kids were cruel (some time I came back to home with chocking marks) and teachers decided to just not see bullying. Or decided to give me a hard time, too. When someone destroyed my textbook by writing on it while I was not at the desk, I got note to the parents because supposedly I told someone to do that.
I kinda liked liceum because finally people were more mature. But man, long term, it was very exhausting. The lesson schedule looked like it was set randomly. For example, in second class, being 16-17 yo, Thursdays I had lessons from 9 AM to 6 PM, and the next day I was starting at 7 AM. I was tired all the time and had no time for social interactions.
Please note that the following paragraph is not personal. It applies to the entire phenomenon. For me, it is annoying when grown-ups tell children that it is the best time in their life. When I was a kid, I felt fear a lot. As a teenager, I was depressed and tired all the time. And, you know, if it is the best time in my life, why should I care about my future at all? It is going to be terrible anyway...
Everyone has its own perspective. Maybe you had great time in school. Maybe for my mother, school years actually are the best years of her life. But telling young people that they are living the best time in their lives, and it will be only worse later, is... unfair.