It was always going to be controversial. I liked the visuals but the script does feel like its for a younger audience. After two episodes, I'll watch the rest - but, I'll watch almost anything with an ancient historical setting.
The show could focus more on the characters and life in those times, than flowing through a series of scripted events. It's the issue I had with Narcos and its docutainment feel when they gloss over important events with a narrator telling you, "...and so tanks besieged the Ministry of Justice, but let's see what happened next." It's a critical moment in the episode and you're shown 15 seconds of archive footage? Then the show moves on.
Of Kings and Prophets could work if they're less about telling Biblical stories and more about introducing new characters and building up a feel for life in those times. Vikings dedicates most of its airtime to side stories, little else but some culture and traditions and it works. And when the big events happen, they're all the more potent for knowing all of the characters who brought you there.