I started it, but didn't find it especially interesting or persuasive. I mean, there's something to the idea of cognitive bias, but I'm wary of anyone who takes a "this one thing is the source of all our ills" approach to ... well, anything. Plus, his book reads like it was written by a 14-year-old who just discovered the Wikipedia article on epistemology and Nizkor's summary of logical fallacies on the same day, and now he has all the answers.

Take for example when he lectures about how the "selling hope" interpretation of lotteries is still bad because it's a "waste of emotional energy." He argues that "maybe" (cue weasel words note a la Wikipedia) people would instead dream about going back to school or improving themselves in some way. He then adds:

Their dreaming brains might, in the 20th visualization of the pleasant fantasy, notice a way to really do it. Isn't that what dreams and brains are for?

Life, according to Yudkowski, is just a matter of maximizing specific bars a la The Sims. If you choose to maximize a different bar, that's a "stupid" or "biased" decision. But he never really makes a compelling case for why his bars are actually better. And at some point, this so-called "rationalist" approach just removes the human portion of life. As the saying goes,

Life is not a problem to solve, but a reality to experience.

In the alternative, XKCD nicely sums up some of my objections.

But I'm not really sure why Yudkowsky thinks that what he's arguing is in some way different or new, especially on things like ethics. He says at one point that

So my values are not strictly reducible to happiness: There are properties I value about the future that aren't reducible to activation levels in anyone's pleasure center; properties that are not strictly reducible to subjective states even in principle.

This idea (said less pretentiously) has been part of pretty much every human ethical system since the dawn of time.

Side note: I couldn't help but laugh when he says, in the same post, "When I'm deciding where to steer the future, I take into account not only the subjective states that people end up in, but also whether they got there as a result of their own efforts" (emphasis mine).

More generally, what I can gleam of his ethical thought seems to go around in circles a lot (but of course, this is the reader's fault), and I'm still not 100% sure what his ethical system actually is.

And, of course, his writings on religion (e.g. here) are so laughably wrong-headed that they border on Poe's Law territory. I'm reminded of the opening line from a review of The God Delusion:

Imagine someone holding forth on biology whose only knowledge of the subject is the Book of British Birds, and you have a rough idea of what it feels like to read Richard Dawkins on theology.

To summarize, my impression is of someone who's trying desperately to systematize the whole of human thought so that (a) he can be correct at will, and (b) can ignore emotions he doesn't want to deal with.