Worf's intentions were good, but he had shortcomings. However, I don't feel it is fair to judge Worf on his fitness to be a parent because we are using human values as the standard by which we measure parenting. By Klingon standards, maybe Worf didn't do too badly, but he had a kid who didn't embrace Klingon values. Maybe Worf's failings may be that he didn't let Alexander explore his human heritage enough instead of pushing the way of the warrior.