Well, the author does have a balanced point of view, but there are a couple explanations for why Whitaker would offer a more reserved view sometimes. First, critics of psychiatry get easily lumped into the 'anti-psychiatry' group where all drugs are bad, which is not where Whitaker wants to be. He knows empirically that this has weakened the effectiveness of critics (like those who get lumped in with scientologists). Moreover, he's just a really SMART person it seems to me. He is more concerned with the truth than an agenda, unlike probably other critics like Peter Breggin, who seem to manipulate much of the evidence.
Also, that Finland program as described in Anatomy uses very few psychiatric drugs, and it does in low doses and tries to keep people off them. Whitaker is just explaining that his opposition is not to 'psychiatric drugs' like some groups, but to unscientific & harmful practices, which is exactly what gives him so much ethos. The Finland program is from what I remember of it, far from modern psychiatric practices.
In fact, in my email communication with Whitaker, he has stated that no patients would miss antipsychotics if they were banned. Based on his books and many interviews/videos I have seen of Whitaker, I think he would probably agree with the statement "The way most drugs are prescribed, they make the illness worse in the long-run." (note I don't know Whitaker personally)
This is a very complicated debate because one can't talk about psychiatric drugs in general, you have to look at the individual evidence for each one. For example, I have much less faith in the Harrow Study that Whitaker cites as evidence that antipsychotics do worse, because I found the critique that its just the worst patients who stay on antipsychotics very salient. This study indicated the health of the off-med and on-med groups diverged after two years (with the off-med group improving significantly.) However, there seem to be a dearth of studies that are this long testing antipsychotics versus placebo (because of the inherent difficulty of that study, I imagine).