The Gun Gale Arc was semi entertaining and had a decent amount of fun action with some character building for Sinon. Sword Art Online again presents a very unique world for us to immerse ourselves into. As someone who played the Fatal Bullet game, I do believe this is a contender behind Aincrad for the best world this series gives us. As for the substance of the season itself, the GGO part was by far the only real part that felt anything worth watching. Again, the second half is taken up by a filler segment and an uninteresting character story. So the review will be about what's worth mentioning.
What they attempted to do with both Kirito and Sinon sharing getting over their PTSD is interesting to explore, but at the end of the day it's nothing more than the surface level plot point. Kirito in particular suffers from them trying to explore his PTSD in the fact that he mercilessly slaughtered Laughing Coffin's guild in the first season, something we see nothing of. We have no attachment to this plot point by extension, and it feels like it was fabricated for this season and wasn't planned beforehand. There was plenty we could have delved into that was already there, but instead we focus on an event we didn't know prior to this season.
Sinon though does get some depth to her trauma, using exposure therapy to attempt to get over her fear. As someone who has tried exposure therapy, it is incredibly difficult, and I feel as though it isn't really given enough attention as Sinon usually has zero issues with using guns. Only the exact model that she shot is what triggers it which begs the question why she's playing in the first place despite not using the gun she has trauma with. The explanation of how the villain worked was also dumb and even though it was supposed to make me feel the tension more, I felt less tension for the illogical approach to the "die in the game die in real life." The villain himself doesn't make much sense as well, and a spoiler warning for this plot point, especially with their ties to the characters and how (one) of their motives doesn't seem to make much sense.
Plus there's still that one very uncomfortable rape scene which is extremely gross but fortunately we don't see much as the previous season. But it starts to beg the question why this is a reoccurring thing the author includes in his works. Seriously, what is wrong with you?
The idea of Kirito having PTSD from SAO was an interesting concept but it wasn't properly explored until the next season. And this is without mentioning again, the second half of the season which is both a filler arc and an uninteresting laid out story for a new character. Sword Art Online proving again that it has no idea what it wants to devote its time to explore. It was meh, and I wouldn't really recommend this to anyone who values their time.