[darktruth]

Like a few others have mentioned, using anime directly as the source of learning Japanese is not a good idea, using it as a supplement however is pretty okay. One way to know that you're making progress on listening is to listen to those drama CDs and see if you have any understanding of what they're saying. I say this because watching anime RAW gives you about 20-50% understanding just from the visuals alone, listening to drama CDs tests your knowledge of tone and context of the situation from the voices. This was how I knew I was making progress on my Japanese after studying it for 6 years in high school when I started testing myself to see if I knew what the characters were saying without any visual aid.