tl;dr
Great plot and general concept but boring character design and artstyle, bland characters decently likeable not too impactful. Setting similar to AOT but not as immersive. Soundtrack is mostly decent. Good show but would not rewatch.
edit after rewatching season 2: Ok this first season is an 8/10 but the last 2 episodes brings it down to a 7 cuz it was boring. The ending song "Avid" is beautiful, and that is made more apparent in episode 22 (s2 episode 11) . Season 2 episodes 1-10 arent worth watching, watch special edition summary episodes instead, they cut off just before the last 2 episodes which are beautiful and worth your time.
Animation, Artstyle, Character Design
I think the animation was just fine but nothing too special, but I truly felt that the artstyle and character design was extremely bland and uninteresting. Our main character Shin looks very generic, along with his whole crew, the main girl's design is slightly better I think but thats just cuz she has white hair and white eyes, but overall extremely average. Maybe its bc I've been watching too much weird stylized shows like Jojos but the artstyle is just so very ugly to me it resembles any run of the mill show released after like 2016. I believe that Shin's brother was supposed to be a cool character and his design was fine but what they did with the legion with his glitching floating head made it all pretty goofy to me. I feel like it made the idea of the legions taking the brains of 86 and using them a lot less intimidating bc it looked so silly. The spider esque robot things they used were also ugly and boring looking.
Character Personality/Likeability
The characters are really not that memorable. Main girl Lena, shin, Lena's other white hair bestie, and shin's tall homie w the scars are the only characters that remotely stand out, maybe also Anju, she looks like maybe she could be part white haired whatever they are called. The rest of the characters in spearhead just seemed llike fodder waiting to die. The main girl was very sweet as to contrast the average white-haired racist characters, but it did seem by the end that the white haired characters we got to see slightly developed, Lena, her bestie, and her uncle all are very aware of the truth and aren't happy about it but feel helpless to do anything about it.
Setting/World Building/Immersion (spoilers for Attack on Titan)
The setting of 86 was quite reminiscent of AOT but far more futuristic. Unless I got something wrong, the 86's brains are harvested by the legion and then they become the legion, which is like how only the eldians can become Titans. The geography with the white haired living in the inside 85 regions and the 86 living outside closer to the battle is like that of AOT as well with the "king" and wealthy living further inside the walls and the poor lived on the edges. Though I did find the explanation of how the legion worked and what it meant for them to take the 86 brains to not make all that much sense, it was confusing. Could be that I didn't pay enough attention but it also makes sense because it is a short series and they dont have as much time to flesh out the small details.
Soundtrack
Some of the OST that was played during emotional impactful moments were pretty damn good, the Opening was average, the Ending song (I think there were 2), the one by Hiroyuki Sawano was pretty darn good. Music was decent.
Overall Plot
The story was good, maybe great at times. It kept me deeply invested almost from start to finish. The main girl was such a sweetheart and it was sad and shocking to find out the truth about the morbid system they lived in alongside her. It was cool to see how the spearhead squadron were used to racist and careless handlers and just expected Lena to be just like the rest but slowly came to realize that she is different and is not a bad person, but even with that they still harbored some ill feelings towards her saying she is naive and too pure for this job.
Impact / Memorability
This honest to god seems like a show I would forget after a few months and completely forget after a year or 2 unfortunately. Hopefully the second season will be able to change that. But from what I hear the second season is not all that much better. I think episodes 1-9 were great, and captivating and kept me on my toes but after their last mission the last 2 episodes were extremely boring with the remnants of the spearhead legion just fishing and hiking around the land. Eventually they got into a fight with some legions and tehre were some humanoid legions running at them that I don't believe had been introduced up to that point, it seemed like at the end they all croaked but since theres a second season with the same characters, they must be alive. Then it ended with lena going to their barracks and finding the cat they talked about and their notes written to her and it was supposed to be touching and emotional but honestly it made me fall asleep bruh.
7/10, was mostly good, fell off towards the end, but i suppose they had to give season 1 some form of closure, hope season 2 is better.