My knowledge of Spanish history isn't good enough to verify the accuracy of the show, but I've read it's quite a bit more faithful to history than "Isabel," although that might not be saying much because "Isabel" gained some notoriety for its dramatic license. What I am sure of is the show accurately reflects the significance and impact of its figures, works, and events from Spanish history. The foreign (that is, non-Spanish) viewer gets a good sense of what Lope de Vega, Lazarillo de Tormes, and El Guernica mean to today's Spaniards.
Finally, I can't recommend this show enough if you're a non-native speaker trying to learn (Castilian) Spanish. First, with Julian (the nurse from 2015), you hear how Spanish is actually spoken today. It's not the Spanish you hear in the classroom, but it is how real, honest-to-goodness, normal Spaniards speak. Then with Amelia (the brilliant university student from the 1880s), you hear perfect formal Spanish - the kind still taught in the classroom. Perhaps the least practical but the most entertaining is the Spanish spoken by Alonso, the 16th Century soldier. Alonso's Spanish is more Siglo de Oro than 21st Century, but it's fun to listen to.
Watch the show because it's massively entertaining. And if you're trying to sharpen your "castellano," you've found a gem in "El Ministerio Del Tiempo." The videos of all eight Season 1 episodes are available on the RTVE website, with captions (but only in Spanish) if you need them.