For one, the story is pointless. Everything is reset after everything is done and nothing has really changed for the main characters. No one dies, no one suffers any permanent calamity. The brain damage threat comes and goes with zero long-term consequences.
On top of that, it's full of deus ex machina and plot holes. How is Yui able to recover the save data still on SAO's server? How the hell is she able to go inside a drone? What the hell is she? Is she a glitch that can enter any form of technology? Things like this can build up and become a problem when they aren't properly explained, and the writers of Sword Art Online have NEVER given a proper answer to what the limits of her abilities or, or even what she actually is. They feel justified in making up new powers for her to have and just expect the audience to accept it.
If any of you don't know, this is what's known as "deus ex machina". The term is used when a show or movie or what have you throws in something that has yet to be introduced without any explanation, usually occurring in the third act. It's also known as an "ass pull", as one would say the writers have pulled it "right out of their ass."
And Ordinal Scale is full of this crap. It cheapens the final battle and turns it into a blowout spectacle, rather than a struggle to survive and advance, which is what Sword Art Online is SUPPOSED to be about.
TL;DR Ordinal Scale is not good. It has all the flaws that SAO 1 and 2 had, maybe even more. If you're willing to ignore the story and just take in the animation and visuals, you might enjoy it. If you're looking for a good story or interesting characters, you may want to look elsewhere.
