The villain is not one-note like what you have seen in the past and how the plot kicks in is both unexpected and gives an anti-hero vibe.
Great action scenes done by various studios beside A-1 Pictures such as MAPPA (Yuri on Ice,Punchline,Rage of Bahamut fame) and P.A Works (Angel Beats!), A story both embracing and warning of the dangers of what while is unlikely could happen to such technology and with themes about PTSD/dementia.
Fan service while in it was only minor compared to even other Shounnen films such as Fairy Tail Dragon Cry and the show itself.
I found SAO to be a mixed bag arc wise but this film is just a fun time to both watch as a story and just as an action flick. This is likely A-1 Pictures masterpiece.
Also stay for the post-credit scene.