Alternative Character Interpretation: Angélica de Alquézar is probably the most debated example. Is she heartlessly taking advantage of the brainless Íñigo, or does she genuinely love him despite her manipulations?
Arc Fatigue: For many people, the fact that Pérez-Reverte is so damn slow at releasing the next installments of the series (earlier ones used to be published three years apart from each other, but five whole years passed between books six and the seven, and the last to date was published in 2011) is a huge point of contempt.
Hype Backlash: While Alatriste will be forever known as the novel series that introduced multiple generations to the Spanish Golden Age, there is also a segment of people that laments that Pérez-Reverte went too far with the cynicism and grittiness of his portrayal, making it look like the period was a full flat Crapsack World whose only redeeming value was occasionally producing honorable footsoldiers like Alatriste himself.
Values Resonance: The King's Gold features a mercenary party that includes a homosexual and a black man who kick as much ass as the rest, yet also manages to never break historical credibility in the process (which might surprise readers that only know The Theme Park Version of 17th-century Spain). This is especially relevant after The New '10s, when many period productions courted controversy for performing unrealistic Race Lifts and historical changes for the sake of inclusiveness.
TV series
Bile Fascination: In an unprecedented case in Spanish TV, viewers actually complained that Telecinco opted not to broadcast the last few episodes of Alatriste despite how furiously they had dissed the series up to that point. Yep, it came a point in which people actually followed the series for how awful it was.
Memetic Mutation: Many people were mystified that Pérez-Reverte praised the series, in special aspects like the story and actors, which were widely considered the vilest elements of the show. This spawned several jokes trying to explain it, often speculating Reverte was being blackmailed, bribed or contractually roped by the producers into giving a positive review (the last theory being also entertained seriously).
Almost every review pointed out that most of the show's attempts at seriousness were failures, often solely due to bad performances and/or gawdy scenography. The villains in particular were hit hard by this, like Malatesta's utterly weird accent or the Alquézar's change from scheming villains into incompetent idiots.
One of the most egregious complaints of the secondary cast was that some actors (hailing from Hungary, where the series was shot) didn't even speak Spanish, requiring them to be redubbed in Spain, which broke completely all the immersion due to the obvious contrast. The character of Vicuña had the misfortune of receiving a very recognizable voice, that of famous anime voice actor José María Carrero, which might only avoid the bizarreness and hilarity because it sadly turned out to be one of Carrero's last roles before his death the same year.
Questionable Casting: The cast was panned by fans and creators alike, noting that it genuinely looked like the casting staff had chosen the worst actor imaginable for every role. Carmen Sánchez and Marcos Ruiz for Angélica and Íñigo were graphically described as looking like "kids chosen by nepotism for a school play", and Luis Callejo as Luis de Alquézar was considered by many as the equivalent of Count Dooku being played by Jack Black.
So Bad, It's Good: Even if the series arguably beats to the punch the infamous Eragon film when speaking about bad book adaptations, its general ridiculousness and shoddy making made it actually pretty entertaining to watch.
Squick: Angélica offering to pay Íñigo with sexual favors is admittedly an element from the books, but in this adaptation, her actress was 14 years old and his actor, while older, only looked younger. How the producers managed to get away with this, even in the early 2010s Spain, nobody knows.
The main fan uproar came due to the series removing what they saw as the most important element in the books, the relationship between Alatriste and Íñigo. In the books, they are literally a case of Like a Son to Me, and the boy's loyalty to him is such that his only reason to be a soldier is to follow the captain to Flandes. In the series, however, Íñigo is completely indifferent to Alatriste and only sticks with him in order to become a soldier like his father, while Alatriste only sees him as an annoyance.
The fact that the series contains so much humor despite the books being almost completely devoid of comedy was not better received than the previous points, especially after finding out that some legitimately badasses, like Quevedo or Sebastián Copons, had been reduced to Bumbling Sidekick roles just to add Plucky Comic Relief.
