I am not sure why they even had the Book of the Beast issue, because they built that up as Witches giving away their free will. Then they basically said she would have to give up her mortal life and friends if she signed. Then we find out neither did it have any impact on her free will nor tie her in any real way to the DL.

In the end of the day she was given power and immortality, but they didn't figure out a clear way it tied witches to him outside of the witches mark idea.

I don't think they thought through Sabrina and her families turn on their deity. It was something they dropped in the span of one episode along with the devils human form. I had trouble buying the parentage revel itself the way it played out. They needed a whole season as in two parts for something as big as the witches tossing out their own version of god not one episode.

The devil went from being a background force, extremely powerful and malevolent and not well understood. But, all important for the lives of witches they ripped the metaphor away and brought him down to Earth so to speak and turned him into a villain of the week who was easier to beat then Batty Bat for the Spellman's.

They basically decided to fundamentally change the basis of the character on Sabrina. I think many may be ok with the decision now, but will realize it was a very poor choice in retrospect after the next two parts play out.