I'd say that any book aimed at learning a subset of Perl to get you started that discusses all buildins is a failure. It's also easy - it's easy to write a book that discusses all buildins. It's much harder to determine a good subset of the buildins.

I can certainly understand if pack and unpack are left out. A lot of programs don't need it, and they are complicated functions, with their own little language-in-a-language.

I used to give Perl courses, and I usually left pack and unpack out. I would only discuss it if I thought the audience could grok it. (UNIX sysadmins with C experience for instance. But I'd leave it out for web weenies fresh out of school - getting them to use an editor was often already complicated enough).