It's a Christmas Carol within A Christmas Carol, and that works. It really does, especially for a children's cartoon. You see the same two stories unfolding at the same time, only to merge into one at the end.
It is cleaver enough where the adults can watch and enjoy it, and Flintstones enough for the kids. And the kids are the intended audience. It is a children's cartoon, but one with enough meat on the bone to keep the parents entertained as well.
And, unlike modern takes, it remembers that Christmas is about love and not spite. Which is always a plus.