Briefl review of the Dune Prophecy series:
This series is set some 10,000 years before the iconic Dune novel. It features the early days of the all-female Bene Gesserit order, and the imperium. A few thoughts (including minor spoilers):
The main conflict in the series is between the early Bene Gesserit order and Desmond Hart, an officer with seeming psionic powers who becomes the most powerful adviser to the Corrino emperor. If you have read the Dune, you know the outcome is foreordained: The BGs will remain powerful, and the new military unit established by Hart will become the Sardaukar. Hart himself won't succeed in crushing the BGs (far from it).
The interesting aspect here is that the conflict is really a fight between two sets of villains! Hart's first major action is brutally murdering a little boy, just in case we are in any doubt of his villainy. The BG leaders (sisters Tula and Valya Harkonnen) are a bit less bad. But Tula still perpetrates a massacre of innocents, and the BG order generally comes off as authoritarian and cruel, even if somewhat less so than the emperor and Hart.
There are a few characters who are somewhat sympathetic, such as the Emperor's daughter Ynez, and some of the rebels trying to overthrow the imperium. But they are much less developed than the villainous leads.
A weakness of the Dune universe is that the institutions developed during this era (BG, Sardaukar, Landsraad, etc.) then change very little for 10,000 years, and tech doesn't seem to advance much either. This degree of stasis is implausible. But hard to blame the producers of the show, as it is baked in.
The villainous nature of all the major factions makes the series kind of depressing, and makes it hard to see what the point is. In the original Dune (which also features evil on all sides), that point is the danger of charismatic leadership. Here, none of the major leaders seem all that charismatic. Indeed, they all strike me as kind of repulsive. Maybe the point is just the danger of power.
Maybe the point is a kind of feminism? The all-female BGs are less bad than Hart and the largely male-dominated imperial house. The original Dune book also shows a male-dominated society among both the imperium and (even more so) the Fremen. As bad as the BGs are, they are not as awful as Hart and the Emperor.
Despite these and other flaws, the series is still fun to watch, and there are some good scenes and lines. If you're a fan of the Dune universe (as I am, despite various reservations), watch it! If not, probably read the first book first.