There is a lot wrong with Dennett's book, but the overarching problem is this. Dennett coins the term "Cartesian Theater" as the idea that all of experience comes together at a unified point for the benefit of some kind of listener. So this contains both the idea of unified experience, and the idea of an irreducible self at the core of the brain.
The unity of consciousness is one of the most important features, perhaps the most important one. Conversely, the idea of a self is so stupid that at no point in my sequence to do I mention it even in passing. It's not logically coherent, it's not physically possible, it's not required for anything, it doesn't help with anything; it's just not something that you need to spend any amount of time on even in a very comprehensive treatment of the problem. But Dennett fails to differentiate between them at any point in this 530 page book (unless it's coming near the end, still not done). The fact that his model fixes problems with the Cartesian Theater is absolutely central to the book; he talks about it over and over again. So the failure to differentiate between them is disastrous, it invalidates a huge chunk of his argument.
Like, the self thing is a strawman even for substance dualism (or what I call Model 1, the idea that C is a non-material thing with causal effect). Model 1 doesn't get a lot of time in my sequence, but even there I don't mention the self. The idea that it's all happening to the benefit of some listener just shifts the problem of explaining how stuff works one level. And if the self is not implemented at all, then this is a priori ruled out by the assumption that the universe follows any rules at all. (Which is actually one of the two assumptions I specifically make.)