I know I'm kind of bringing this thread back from the dead- I hope that replying to a thread that's two months dormant isn't considered rude here. I did want to toss my two cents in here though.
First off, it really is important that you not _emulate_ anime speech when speaking Japanese, if you don;t understand the implications of that speech. It's not just a matter of levels of formality. If you are a beginner at Japanese that's going to be pretty obvious to a native speaker of Japanese, and they'll likely forgive you for using plain speech rather than teinei (every-day polite) speech. I guess you know the old saw about the dog who speaks- it's not that he speaks well, it is that he speaks at all. So if you bust out some garbled Japanese you learned from anime you will likely just get a pat on the head, if the only problem with it is that it is too informal.
The problem is that anime characters often use language that is _really_ rude. In the worst case you might pick up the idea, from certain anime series, that it is OK to refer to other people as "kisama." If you actually do that you are not going to get a pat on the head, even if the Japanese person you're talking to realizes that you don't know any better. Just like a Japanese person who introduced himself to your grandmother by saying "Hey, how you doing, you [word that is pretty much the least acceptable word in American English, but is more widely used in British English]?" would cast a pall over the room even if everyone there understood that he didn't know any better. The difference is that you will hear language that rude in a mainstream show for Japanese teenagers, or kids, even, because rudeness in Japanese is more contextual than obscenity in English- it's fine to depict it

.
Even if you know that kisama is verboten, you might pick up the idea that it is OK to call people "omae," for instance. You won't see anyone in HnG calling anyone "kisama," but _everyone_ is "omae" to Shindou. That's still pretty rude.
On the other hand, I think it's fine to pick up Japanese from anime, as long as it isn't your only source. I learned Japanese mainly by listening and reading, and a lot of what I listened to was anime. But I also got a couple of textbooks, meant to cover two years of intensive University Japanese. I didn't use them the way I think I was supposed to though- I read the first year's worth in about 2 weeks, skipping all exercises, and not worrying about learning the vocabulary from lists. Then I watched a couple of hundred hours of Japanese TV, and reread it even faster, and read through the second year text in a couple of weeks. I was simultaneously reading some parallel texts.
I took a couple of years of intensive Chinese in University, which was longer ago for me than I want to admit. My Chinese is pretty abysmal- that's partially because of disuse, but I was never able to just pick up a Chinese novel and read it, or just watch a movie in Chinese. But within a couple of years of starting to learn Japanese I was able to read contemporary novels and watch Japanese dramas without subs, and without missing all that much.
I might have spent more time on the Japanese than I did on the Chinese (or maybe not- I had Chinese Chinese professors who assigned an insane amount of drudge homework, so I really did spend a lot of time on Chinese when I was in school.) But the Japanese never felt like drudgery, since I never pushed too hard on any one thing (and also because I didn't have a Chinese guy shouting "dui bu dui?" at me, and spitting on me, every few minutes...)- if I had a hard time understanding a point of grammar I skipped it, and it generally turned out that a while later I had come to understand it without knowing when I had. The only thing I ever really studied was vocabulary, and I didn't do that until I already had a strong core vocabulary of a few thousand words- enough for most situations, but not enough to read literary novels from the early Shouwa period, say. Well, I still have problems with Souseki, to be honest.
I think it is really counter-productive to "study" a language. You want, I think, to treat the whole thing very lightly. Read through the text very quickly, get what you can get from doing that now. Watch some Japanese TV, and try to hear things you noticed in the text. Go back to the text for answers occasionally, and seek out more advanced texts (which are hard to find, since 99 out of 100 people who start learning Japanese never get past the two intensive semester level, which is maybe 15 kyuu in Go nomenclature, if we are being generous. There is a huge market for beginner books, but very little market for more advanced books, outside of Japan) when you can't find explanations for what you are hearing in the basic texts. And have some faith- what seems mysterious today will seem obvious in a while, even if you don't try to figure it out.
EDIT: BTW, most texts are also likely to lead you astray here. They tend to introduce the word "anata" as if it were equivalent to the English "You." If you take that literally, as most students of Japanese do for a while, the result is going to be very unfortunate. The texts should hang a sign on that word: "Be very careful about using the word 'anata'." But they don't, generally, and that is really worse than 95% of what you might pick up from anime.