If you’re willing to give it the space needed I’d definitely recommend The Unconsoled[1]. It’s by quite a long way the best description of dream state that I’ve ever read.
It seems to me that the value of unpleasant art is usually that it teaches us something: perhaps it helps us to empathise with people we previously didn't understand, or gives us a new perspective on a topic we care about, or makes us care about a topic we had previously neglected, etc. But if The Unconsoled precisely captured a feeling you were already familiar with, all I can see it doing is giving you a sense of connection: ah, yes, someone else really does get what my nightmares are like; I'm not alone. Which is not worthless, but seems likely to be outweighed by the unpleasantness of the reading experience.
Am I just wrong on that last point, or have I missed something else entirely?
I can say that I've "read" more Ishiguro through audiobooks than paper, and that they've all been excellent. Rosalyn Landor's Never Let Me Go was particularly moving.
The first-person perspective used by Ishiguro in several of his novels lends itself very well to the format. When We Were Orphans isn't typically considered one of his stronger works, but as a "told tale" I found it fascinating.