The idea to learn language while doing something fun is great, but... It can't be like in this game. There is no actual goal (except for time attack mode). If it had some kind of quests, where you have to learn a word or a sentence to get further it would have been more useful. Like this - it's pointless. You just walk around and click on things. I believe it would be cheaper to get a simple old-school vocabulary. Or like Lingvo...
I remember, when I was learning English there was a game for native English speaker to learn the language. I mean for kids. It even had a story, a whole map and a bunch of playable characters. Gameplay was made of moving through map and solving different puzzles and or playing mini-games, where you had to find a correct word suiting the situation, make a sentence. Some games were simply for learning new words or even some grammar rules. Too bad I do not remember the name of the game.