This anime is good. 10/10 in fact. I too am surprised when i first watched this anime. I mean, who wouldn't? In terms of overused materials, this anime got them all. Cliché plots, generic kirito-type character (they even got the same seiyuu wtf), cringe and emo MC, i mean damn, you name it all.
But the real reason why i rated this anime a 10/10 is because of the plot itself. It's clean, it's bland, and it doesn't even have any new contribution to the isekai genre. I might have rated this anime a little bit too high but please listen to what i have to say.
This might be a little bit too scientific. If you're one of the people who said "SAO is bad because tons of people say it's bad." then you're free to not read this essay.
What i want to explain, is about how clean the plot is. You might think it's lazy to make such a simple plot, but being simple in the world of infinite possibilities is actually the hardest thing to do. The author brilliantly starts and ends an arc without a single space for the sense of "uncomfortableness" to fit in. Yes, it might be cliché, but the cleanest of it is also something we need to give credit to the author. (I mean, making a long story without once making the readers feeling weirded out is extremely hard.)
Diving from one arc to another. It's really clean that you could even see the plot structure and it's especially good if you're learning how to write an engaging story. Basically like Nemo and other Disney movies that are also clean and solid in terms of plot structural management, but in anime version.
I'm not the type of person who would say "try making a story and see how hard it is". I understand that Seirei Gensouki is lacking in some parts like the art and the sound quality. I also understand that people are trying to find newer and more engaging stories to watch and were certainly disappointed after watching this. But if someone were to ask you how is Seirei Gensouki, you can say "Yeah it's pretty bad but it also got some good points in it" so you can sound a bit more intelligent. Or don't follow my advice im not your mom