As an early student of Japanese, you'll learn that there are some clear-cut grammatical rules of formality. You'll learn that, for example, there are three variations of any given verb that you need to carefully choose to suit your conversation partner and conjugate much as you would a past or present tense. In the most honorific case, there are sometimes entirely different words (the verb "to eat" is one example).
It's a concept that can be very frustrating for Western students. Not only is it more words and conjugations to memorize, it can also be awkward at first to carry on a conversation worrying all the while that you might trip up and say taberu instead of tabemasu—or worse yet, kuu. It can also be trying to come to acceptance of your place in the world of katchos and buchos and kakarichos, and I've seen more than one student reject the role handed down on them and wonder out loud why everyone can't just talk regular.
But for how tedious the memorization and how embarrassing a slip up can be, it's one of those concepts that Western students can accept pretty quickly—unlike verb tenses and the lack of pronouns. It just makes sense. We all know that Japan is a ridgedly hierarchical society in which all members consciously act according to their understanding of their place, right? Stereotypes and cultural anthropologists drill it into our skulls that to understand the Japanese hierarchy is to understand the Japanese.
At a bar in Hokkaido one night with a group of Japanese and non-Japanese friends, one Japanese woman spoke to a new member of the group (an older doctor) in a very informal tone. An American woman in the group, who had just started learning Japanese and was herself experimenting with the levels of polite grammar, immediately picked up on it and jokingly called the woman out for not using the proper formalities of speech. The Japanese woman looked at the American completely bewildered: she spoke naturally to the older doctor, and no one in the group was offended or even surprised by her tone.
I was immediately struck by what should be one of the most obvious lessons: the grammatical rules of formality are well known to the Japanese, indeed they're even named, but they're almost entirely subconscious. The formality level that Japanese people speak with is partially based on social status and partially based on their own personality, which explains why someone older than me might speak formally to me while another guy might mix the rough ore ("I") with a desu/masu-kei verb.
It was an important point where I stopped thinking of Japanese as a foreign language with daunting cultural and grammatical mountains to climb. I realized that Japan's hierarchy can be as fluid and flexible as it is in the West (even though we Westerners often don't like to think that such a hierarchy exists in our society), and our speech is allowed liberties. It's more important for us to find a mode of speech that's comfortable, fitting for our personality, and suitable for the situation—exactly what we do in our own languages.