I don't think that matters that much (the book material i mean).
He's never been a story heavy director, Blade Runner is a detective movie where there is no mystery, and the protagonist has nothing to do for 2 hours, it's basically all standing on visuals and his ability to sell a mood, a world.
Ability that he still possesses, as seen in Prometheus and Covenant (who most people criticize for plot holes and use of symbolism).
The man spent half of his career directing commercials, where the only concern is to sell strong, striking images, in a matter of seconds; that's been the strength of his movies since the beginning.
I don't understand this myth of him "going senile" you always read, since his latest movies shine where his older ones always have, the visual compartment.
As for him being pretentious, this is a word that lost most of its meaning, but he mostly seems to be obsessed with a couple of themes he returns to, over and over (and does so in Raised By Wolves, too) of religion, spiritualism and science.
And he does so in the way he's always known how, and always done: With strong, in your face imagery (like a 20 seconds commercial!).
Not even saying Prometheus and Covenant (which i assume are the reason for this myth) are perfect movies, far from it, they are littered with nonsensical plot holes, stiff dialogue and generally some narrative structural messes, but the core of what made his cinema great in the past, is still there.
He's never been the best director ever, but i think people completely overblow his supposed decline.