More often than none, you get out of it what you put into it. A formal learning program will encompass a wealth of information in a logical and structured manner along with labs to prove the theory. Doing this on one's own is possible only by the most determined and diligent ones. It's also nice to have an instructor present to further enlighten you as well as answer questions. Most importantly, if you ever want to persue a career in the field, employers will want real documentation such as diplomas or certificates rather than one's "word" that they are self-learned.