My jaw dropped after seeing the reviews for the season finale, I was really disappointed at the community and this site in general. How can you rate such a well executed and series defining season as anything less than astonishing?
First and foremost J.C hired the author to supervise development in order to keep the lore as faithful as possible to the original work. I mean the season was actually canon compared to the bullshit scripts they used in their first two seasons. Perhaps there were a few intricate scenes that weren't added in which the fans were expecting to see but apart from such
gratuities they shouldered the light novel's burden with very few inaccuracies keeping it faithful to the books until the end.
Now most hate originates from the sudden and vast amount of change, and I mean it's so grand that the setting itself is at threat. Tons of new characters were introduced and many returning characters who played previous core roles came back to be sparsely used and receive small insignificant ones such as Yoshida who made little appearance to the exception of the start and end of the series and even then she was vaguely there. Though there may have been many new characters, those new roles added a lot of flavour to the show incorporating many new personalities ranging from the daredevil rebecca reed to the subtle, shy rose shaped cocytus brigid.
Apart from all the added characters the two that the series depended and revolved around also underwent change. The protagonist and the heroine or should I say the antagonist and the heroine? At the beginning of the season the boy dotes upon the philosophy of change and what it would accomplish if he were given the strength to change the world and eventually under the influence of the deity Serei no Hebi(voiced by AYAMI SHOW) he takes the task to achieve a better tomorrow for his friends family and loved ones, but to the expense of the girl he loves whom he has to fight against in order to save. At that moment and as we progress through the series we get glimpses at how drastic his personality has shifted from a scared boy who let the surprise of the moment swing his mood to a daunting young man incorporated with the traits and charisma of the Snake. This was what I think J.C struggled the most with, shaping Yuji's character to one that represents his ideal self influenced by his decision to change, and the half shared by the deity. Though they are the same entity they both have distinct voice actors, one that portrays the newly reformed Sakai Yuji and the other that reflects the snake's wisdom.(Who can do a better job than AYAMI SHOW for an immortal badass snake that has lived for over a millennium?) Although they've never contradicted the other the two are easily seen as different individuals who can be distinguished even if they bore the same voice. Despite Yuji's polar change at the start of the season he also grows on certain occasions where he's given the opportunity to confront his old classmates he left behind giving a thorough speech to them on his motives and reasoning behind fighting against what they perceived as good and clearing any misconceptions the viewers may have formerly had.
As Sakai Yuji develops a more complex character the same can be said alongside the heroine Shana who struggles against her own insecurities the first half of the season and turns into a fine dependable young woman the next. Her personality at the start is a port from the second season as she slowly realizes her own true nature and strength which she later demonstrates against Sakai Yuji who defeated her in Misaki city. Following her defeat she learned to quell the emotions and feelings she couldn't answer and confessed to him when they met proving her own desire to change that rivalled that of Yuji's actions. Shana's change wasn't as notable as the Prota/anta but it was without a doubt more character development in 10 episodes than what you would see in 100 naruto episodes.
Well it's true that the season lacked in the harem department but the scenes involving Shana and Yuji confessing their ideals to each other and how they fought for a better future together were more emotionally involving than the entirety of the second season. I fail to see how some found the season boring, I obviously don't share in your opinion since I remember the great deal of satisfaction I felt at each episode when the series was still airing and the yearn for episode 12 after episode 11 ended on a cliffhanger and had the next episode delayed for two weeks.