If you watch enough anime with english subtitles, you pick it up a lot quicker. A former friend of mine is something of a linguist, and she said it's one of the easiest languages she's learned, and a lot easier than German.
It's better to watch it through completely raw (no subtitles) first before using subtitles. Try to figure out what's going on first and see if you're right (plus it helps you focus more on pronunciation and grammatical structure as well as slang, tone, and dialects.)
Indeed. My thoughts exactly.