What they got right: I'm not all that knowledgeable about the Shazam! universe, so I can't compare this version of Kull to a previous one, except I pretty sure he was in the Booster Gold episode of Batman: The Brave and the Bold. He does seem to be a formidable foe for Captain Marvel, and a caveman who has technology more advanced than ours? Silly, but works with in the Billy Batson world.
What they got wrong: Most of the character models are well drawn (Mary comes off looking like a Kewpie doll), with some amazing artwork. So why is that "wrong"? Because it's wrong for this title. Whatever problems I thought the last issue had with a poor rendition of the Kunkel models for the Marvels, at least Vaughns made it look all cartoony. This is more like the old comic designs, only the lines are too dark. Also, I didn't know the Rock of Eternity was in outer space, as it seems to be depicted here.
Recommendation: The art is good, but doesn't quite match the series. The story is decent, but feels like a filler story more than a continuation of the "Sivana is back" plot. None of that keeps it from being a good read, though.
