Hmm, although I am tempted to say: "kanji, Kanji and KANJI!", I learned to appreciate what kanji does for japanese.

Since there are only a few sounds possible and limited combinations, japanese has many words that sound pretty much the same (Im not even considering que ones that are pronounced slightly differently). The only way to know what the meaning is is through the context or Kanji . A text written only in kana would be pretty much indecipherable, due to the lack of spaces between words. So, although Kanji is hard, I love them and i am having a blast learning their meaning and seeing how they are put together.

One thing that is hard for us Gaijin to understand is the speech itself, how is constructed to be vague and not offend the other person. You are not to pull the attention to yourself during conversation, so the word "I" is not used as frequently as in English or Portuguese. And that is a hard concept do grasp, since it's so cultural.