I can tell you that the two languages I can confidently say I know well - C++ and Common Lisp - are the ones I learned from books. The rest I learned from various on-line tutorials, articles, references and sometimes from half-reading a book - and while I can code with them, I can feel my coding in them is mediocre. Hell, I feel that the generic-coding skills I have I owe mostly to books (and practice). You can't beat a book in terms of depth and undestanding.

(And don't get me started on videotutorials. This is probably the least cost-effective educational medium ever invented.)