This game is great for people who want to learn Japanese, but it may not be right for everyone.
When you first start the game you have to take a test to see how well you know Japanese already, and if you do well, you go straight to lesson 11... Out of like, 1000+ lessons. Wow. For me playing the game is a good review for Japanese that I already learned, but once you get into the later lessons the vocabulary gets more and more difficult, and I had problems with a few of the words. Also, the mini-games aren't all that great. My least favorite is the Wack-A-Mole game because it is very tedious to keep pressing the screen on the moles in my opinion. I like the quiz games and the spelling games however.
One main problem I have with this game is the stylus detection. It doesn't seem to work well at times, especially when you have to write the Kana characters. I feel like I can't write the characters the way I write them on paper; They force me to write them in a VERY specific way. It gets very annoying.
However, I like how there is a dictionary in the game where you can see all words (Except slang and swear words) and hear how they are pronounced, and the conjugations for verbs. Great tool.
Overall, I would recommend this to anyone who either took/ is taking Japanese in school to use as a study tool or for people who never did and learn from the game. However, this may not be the right choice for everyone so approach this game with caution.