This is me paraphrasing someone else on Wrong Planet, but I completely agreed with that person. In terms of describing what it's like to be autistic, it's very good. As a theory of the cause, it's pathetic. There's a short blurb that toxins might be the issue, but that's it. "Theory", I don't think it fits. A description of the difficulties we go though, I love it.
The Neanderthal theory of autism, while based more off anecdotes, and biased in that the results are based off the Aspie Quiz (so no real control group), it does make a lot more sense, at least to me in terms of being an actual theory. Reading some of the criticisms of it, I'd say they're very valid. But what I truly liked about it, the theory starts with the idea that autistics aren't defective. Even excluding the valid criticisms, some of the ideas are definite stretches from the data. But in terms of an actual theory vs the intense world, the Neanderthal theory blows it away.