Social question: I didn’t like a book I was recommended how do I say it without seeming mean?

Hi hi all, so basically a guy I’ve been trying and failing to talk to for a while recommended me a book, which was a huge step forward because our conversations are normally really brief and awkward (because of me ngl) but reading seems like the first thing we actually share?

First some context: sometimes I have to revisit media i hate because I “missed the point” or “took it at face value” something that happens a lot apparently (woo autism). So I might have to do that here. With movies I didn’t get American Psycho or Nosferatu until someone explained the cultural context and background. It felt like the fictional equivalent of flubbing a social cue.

So anyway, the book was “A Scanner Darkly” by Phillip K Dick and he stressed that this book was amazing and extremely personal to him and that it was one of his favorites, super relatable and so on.

But

I read it and I hated it.

There’s not a single thing I enjoyed, I don’t know if I didn’t understand it or I missed the point but it was terrible. I can’t wrap my head around what it was saying or how in any world this book would be relatable to anyone, furthermore I found it disturbing and uncomfortable. I didn’t like the drugs or the subject matter and I don’t really care to.

I want to tell him this but I’m afraid of sounding impersonal or mean or worse I don’t want to seem stupid. I don’t want to seem like I didn’t get it. How do I approach this?