Oh, and you'll grow to love kanji.

To the point where you'll wonder how you managed without them. There are generally no spaces in Japanese, so you learn to break up text according to kanji. When they're taken out of the equation, you suddenly find that your reading speed is completely crippled. I've tried playing old NES-era RPGs that are exclusively kana, and I honestly find it more difficult than modern ones that are full of complex kanji.
Once you've learned kanji, you'll also coast through vocabulary acquisition, since thousands of words can be acquired by simply sticking two or more characters together in (generally) logical structures. You'll also experience the cool phenomenon of reading and understanding words you've never seen in your life based solely on the kanji involved in them. :'D