First off, the good:
The book, with its unreliable narrator and the style of requiring the reader to piece together an incomplete puzzle, can serve as a starting point for many interesting discussions related to the theme of robots. However, this is not really the point of the book. But rather a red herring.

What the book is at its core, is a discussion of humans' need for servants and hierarchy. Reading it with those optics makes it much more interesting and unsettling.

Klara is programmed to accept her status and what she "is" in relation to humans. This means that this book as it's most interesting is not about if robots can be humans or not, but rather about the human need for slaves or obedient servants. This is what makes the book the most interesting. It is a meditation on how humans relate to other things, and what we treat with dignity and not.  How do we treat things which are not human? 

Plus for good use of language.

Challenges the author has not solved that well:
The robot is the only narrator. Choosing the robot to be the only narrator means also having to address the mediation of machine vision, which sometimes does not escape an anthropocentric point of view. Is this really a robotic narration, or rather how a human envisions a robot reflecting? This narration humanizes her for us as readers.

This is for instance related to narrating how Klara literally views the world, where she is self-aware to some point about viewing her own software which is also visibly asserting itself in her field of vision. although there would be no need for this, as there is no human looking at an enhanced screen, rather the data would directly be processed without an outside view of it. Therefore, the inclusion of how Klara sees through boxes that sometimes appear seems to defy the logic of how she is software. There is no need for her to be made aware of what she herself is computing.

The second concerns her using the same language for talking about her feelings as humans would. Her feelings are limited to feelings that are positive to her servant family. She is also incapable of feeling any negative feelings, so it is clear that she is programmed to some sort of experience, but what are they really? The lack of negative emotions means this is something incapable of suffering. Which means it is not sentient.  However, as the narrator, the AF is anthropomorphized for us as readers. But it could be questioned if this is done with the intention of making the lack of dignity the humans in the story treat others with, including the AF, more visible for us as readers. 

As readers, we, therefore, relate more to her than the humans she is living with would. Because as readers we relate to "feeling of joy spreading through me". the humanized narration can lead us to believe a calculated answer by complex algorithms has led Klara to the conclusion that the Sun is an all-powerful god.

Other negative things:
Ishiguro for some reason introduced a bit of magic realism to the story so we could always say "oh but MAYBE The Sun is a god after all" which I found a bit unnecessary.

Minus for terrible unrealistic dialogue between kids/teenagers and portraying realistic teenagers. 

Read the novel, then read this article: "Artificial Animals", https://www.growbyginkgo.com/2022/01/18/artificial-animals/