I read the book, it was interesting, however a few points.

• Rather than making the case, it was more a plea for someone else to make the case. It didn't replace the conventional theory with its own one, it was far too short and lacking on specifics for that. If you throw away everything, you then need to recreate all our knowledge from your starting point and also explain how what we have still works so well.
• He was selective about quantum physics - e.g. if reality is only there when you observe, then the last thing you would expect is a quantum computer to exist and have the power to do things outside what is possible with conventional computers. MWI predicts this much better if you can correlate an almost infinite amt of world lines to do your computation for you. Superposition/entanglement should just be lack of knowledge rather than part of an awesome computation system.
• He claims that consciousness is fundamental, but then assumes Maths is also. So which is fundamental? You cant have both.
• If we take his viewpoint then we can still derive principles, such as the small/many determine the big. e.g. if you get the small wrong (chemical imbalance in the brain) then the big (macro behavior) is wrong. It doesn't go the other way - you can't IQ away your Alzheimer's. So its just not clear even if you try to fully accept his point of view what how you should even take things. 

Great you bring up Hoffman; I think he deserves serious pushback.

He proofs exactly two things:

• Reality often is indeed not how it seems to us - as by much too many, his nonsense is taken at face value. I would normally not use such words but there are reasons in his case.
• In as far as he has come to truly believe all he claims (not convinced!), he'd be a perfect example of self-serving beliefs: how his overblown claims manage to take over his brain, just as it has realized he can sell it with total success to the world, despite absurdity.

Before I explain this harsh judgement, caveat: I mean not to defend what we perceive. Let's be open to a world very different to how it seems. Also, maybe Hoffman has many interesting points. But this doesn't mean, his claims are not completely overblown - which I'm convinced they, are after having listened to a range of interviews with him and having gone to lengths for reading his original papers.

Here three simple points I find compelling to put his stuff into perspective:

1. You find a moaning gap between his claims and what he has really 'proven' in his papers. Speech: "We have mathematically proven there's absolutely zero chance blabla". Reality: Used a trivial evolutionary toy model and found a reduced form representation of a very specific process may be more economical/probable than a more complex representation of the 'real' process. It nicely underlines that evolution may take shortcuts. Yes, we're crazy about sex instead of about "creating children", or we want to eat sugary stuff as an ancient proxy for actually healthy diet which in our today's world doesn't function anymore, and many more things where we've not evolved to perceive/account for all the complexity. Problem? Is of course nothing new, and, more importantly, it doesn't proof anything more than that.
2. I like the following analogies:
   1. Room-Mapping Robots vs. Non-Mapping Robot cleaners (Roomba stuff). A not too far-fetched interpretation to Hoffman would be: A (efficient) vacuum robot cannot map the room, it's always more efficient to simply have reduced-form rules/heuristics for where to move next. Well, it's nice to see how the market has evolved: Semi-random moving robots made the start, but it turns out if you want to have robots efficient, you make them actually map the territory, hence today LiDAR/SLAM become more dominating.
   2. Being exposed to a cat, I realize she seems much more Hoffmanesque than us. When she pees on the ground, or smells another weird thing, she does her 'heap earth/sand over it' leg moves, not realizing there's just parquet so her move doesn't actually cover the stink. It's a bit funny then, with Hoffman the species that has overcome reliance on un-understanding instincts in so many (not all) domains, is the one that ends up claiming it would not ever be possible to overcome mere reduced-form instincts in whatsoever domain.
3. Trivial disproof by contradiction of Hofmann's claim of having absolutely proven the world could not be the way we think: Assume the world WAS just how it looks to us. Imagine there WAS then the billion-year evolutionary process that we THINK has happened. Is there anything in Hoffman's proofs showing that, then there could be only dumans, like humans but perceiving in 2d instead of 3d, or in some other wrong-way-with-no-resemblance-to-reality? Nope, absolutely not. His claims just obviously don't hold up.

Broader discussions highlighting I think in part some fraudulent aspect of Hoffman: The Case For Reality, or also Quora Is Donald Hoffman’s interface theory of perception true? 

In sum: His popularity proves an evolutionary theory for information where what floats around is not what is shown to be correct, but what is appealing; distracting voices debunking it being entirely ignored. I imagine him laughing about this fact when thinking about his own success: "After all, my claim seems to not be that wrong, they do not perceive reality, mahahaaa". According to google there are not merely a million people reading him, but literally millions of webpages featuring him.

Happy to be debunked in my negative reading of him :)

More sophisticated mechanisms (those that can extract more information) are, generally speaking, more costly.

At some constant level of complexity/cost, some mechanism of perception can extract some certain amount of actionable information from what it perceives. There is then the question of which bits of information to extract.

Such bits of information can be more or less veridical (information that closely tracks what is true about what is perceived) or practical (information that closely tracks whatever is relevant to the fitness of the perceiver).

These do not necessarily track one another. In other words, one bit of practical information (X is/is not relevant to my fitness) may not correspond to one bit of real information (X is/is not quite like so). Hoffman believes that this is typically the case: that practical perceptions do not represent actual facts, but are jumbled up functions of facts about what is perceived, the context in which it is perceived, and the state of the perceiver. We cannot easily disentangle this and go backwards from our perceptions to try to recover just-the-facts.

Natural selection will favor perceptive apparatuses that extract practical information; it will not operate to preserve equivalently-costly ones that extract merely veridical information. For this reason, the latter don’t stand a chance.

Ergo, everything we perceive is natural selection’s attempt to give us handles we can manipulate to increase our fitness. We have no reason to expect that such handles represent what “is there” or exists outside of our own interfaces. (You may say your interface has the same icon on it that mine does, and that it behaves in the same way in your interface as in mine, but this does not prove that we both have true representations of some underlying fact, but merely that we both have similarly-evolved interfaces. We both say the stop sign is red, but it isn’t.)

I don't see why that would apply to humans , since we have very large brains and for ibke behaviour.

An organism that exists in a simple life-world and has limited resources can filter out irrelevant information at an early stage of neural.processing...more perceptual than cognitive. For instance, a frog sees the boundaries of its environment (but no detail within them), small, fast-moving objects, which are reflexively treated as food, and large moving objects,.which are reflexively interpreted as threats.

An organism that exists in a complex life world can't use simple perceptual processing to differentiate food from threat, because both exist in wide varieties. There is a limit to how much information can be hardcoded into a genome as opposed to stored culturally/memetically , and an even bigger difference in flexibility.

If a certain vegetable is poisonous unless it's cooked in a very specific way, is it food? It's food if it's cooked in the right way...eg. manioc... which is culturally transmitted information...

but you have to be able to see it , before you can figure that out. Heavy perceptual filtering would make the cultural discovery impossible. Relatively unfiltered perception is a necessary but insufficient condition for memetically transmitted knowledge, which is much more powerful and flexible than genetically transmitted knowledge.

So the frog like organism that goes for heavy filtration achieves efficiency up to a point, but places a ceiling on it's ability to exploit an environment, particularly a changing one.

No organism has a complete view of reality..all are limited by how far they can see, what frequencies they can detect. In that sense, nothing perceives reality in the sense of all reality. But within that category there is an important difference between the stimulus-response organisms and the cultural learners.

All of the stuff we take for granted as making up the world we inhabit — objects, dimensions, qualities, time, causality — are, says Hoffman, not objectively real.

I expect these words to be followed by a redefinition of what "objectively real" means.

There’s really just no resemblance between the interface and the underlying reality at all.

Well, maybe no resemblance of... uhm... the substrate, for example we could be simulated on a computer, and the stuff our universe is made of could be completely different from the stuff the computer is made of.

But there is also the resemblance of... form, like if we experience something in our universe, it is probably in some way represented in the simulated computer. Like, the things we perceive as the laws of physics are in some way a consequence of something in the simulating software. Maybe not 1:1 directly; it could be the case that something we perceive as a basic law could be just some statistical average of the true underlying law.

What I am trying to say is that if our perceptions were utterly disconnected from the true reality, then we wouldn't be able to make any kinds of predictions, and probably couldn't even live.

So what is reality composed of? Hoffman’s bet is that it’s consciousness all the way down.

That would be a consciousness of someone who is really obsessed by calculating zillions of numbers precisely. Some kind of Divine Autistic Nerd.