Well I’ve found having children has changed my life, but I would argue over whether they’ve actually improved it. In practical terms, I would say my life is worse now: more stressed, less sleep (they’re teenagers now but I’ve not managed to sleep well since dd1 was born), much less money, less freedom, and going back to the anxiety: since becoming a parent, I have experienced a level of vulnerability that is like nothing else; my happiness is based solely upon the health and happiness of two others. It is also draining, thankless, and the domestic workload has more than doubled.
Spiritually though, I would say it has improved. I am not the person I was pre kids. However; whether I would be this same person after fifteen years of NOT having kids I’ll never know.