Fairy Tail's final season left me disappointed. I especially enjoyed Fairy Tail Zero, and the Tataros arc while full of plot armor was still decently enjoyable. This season had its moments, but ultimately I didn't enjoy it as those 2. It also left me confused, as there are many plot points that don't add up, or are just thrown out there to either make the season more interesting, or keep the viewers interested without basis.
Story: The beginning of the final season is essentially the Avatar Arc, and at first they look like the main villains of the season, but they turn out to be incredibly weak and just fodder. You could skip those episodes and miss absolutely nothing. Ultimately, the main villains are the Spriggan 12, who act as Zeref's personal army. They all have insanely powerful abilities, and apparently are apart of the Alvarez Empire, which is extremely wealthy and powerful (but for some reason we don't hear anything about them previously. You'd think such a powerful empire would at least have been known well earlier in the series). They basically battle against Ishgar in addition to millions of other soliders from the Alvarez Empire (this all happens because Zeref is bored, I guess and wants Mavis. Great reasoning there by the smartest main character in the series). Many other guilds join in helping Fairy Tail, notable ones include Sabertooth and Mermaid Heal.
Animation: The animation is solid. Character designs are pretty good. I like Ajeel's design, and God Serena's is interesting. Not much to complain about here.
Sound: I've never been crazy about the Fairy Tail soundtrack throughout the series, but it does fit the story and the theme of the guild. So while I may not be a huge fan of it, it does fit the series pretty well.
Characters: If you're interested in the final series, chances are you probably already know who the main characters are, what their personalities are, and what there relations are with other characrers. So I'll use this section to talk about the Spriggan 12. I'm not a fan of them. Many of them have either have bland and forgettable personalities (outside of the eccentric God Serena, though we barely see any of his fights and Wall Eehto), or are extremely overpowered and use their abilities poorly (Jacob and Brandish are notable in this). Irene and August have the most overpowered abilities, and have their fights end due to plot armor. This whole series was poorly written.
Overall: This season disappointed me a ton. Too many things don't make sense (how does Erza struggle to defeat Ajeel who's one of the weaker Spriggan 12 members then suddenly punch a meteor controlled by Irene) and the new villains are not interesting and lack character development. It feels like this season was rushed. I understand the anime tried to stay consistent with the manga (which I read and also didn't like in terms of the final season), but for such a popular anime to close out this way, especially when some seasons were great, it's disappointing.