So far I have just poked here and there in your draft, but I think this will be a really great book.

But here is something I would not like as a reader (as I said I have not yet read anything so sorry if I have overlooked stuff):

In Chapter 3, "Unicode in Your Filehandles" you introduce the notion of a filehandle without any explanation at all. In the code the autodie-pragma falls from the sky (finally explained in Chapter 11 I think) and you use the <>-operator, again without any explanation.

Who is the target audience? As a novice I certainly would be confused at this point.

I would add a chapter (or a section) about strict, warnings and autodie before this as well as a chapter (or section) about file-handling (explaining filehandles, open and <>).