[Jaydelart]

I disagree, Baka.
Although, generally, you may not be able to learn the entire language through anime, it may still provide some valuable insight into it.

*I do know a few people who have learned a great deal of Japanese through anime. Of course, they'd been watching them since they were very young.

It is known that you can learn a language easier when you hear it being spoken often.
What makes (undubbed) anime any different? The voices in anime, afterall, are usually spoken by real Japanese speakers; therefore, you are somewhat receiving "real life" exposure to the language.