I was really hesitant about getting it, in fact I never even heard of it until I rang it up at work for a guy, who happened to be asian actually.
It wasn't badly priced, $29.99 - 27 after my discount -- video games suck for discounts.
I looked online to see if it was actually beneficial and there were looots of reviews for it. The people who spoke japanese fluently complained that there was too much romanji in it - but they defended it as well that if they didn't start out with romanji people would be scared away.
Another big down side is stroke counts. The order of strokes in a symbol is wrong and apparently it's very important for the order you do your strokes.
I ended up getting it because I figured the least it could do was raise my vocabulary. I've already discovered I'm bad at speaking it. The way I pronounce words and the way they do it completely different at some points. I got the annunciation down, I knew that before I played, but the stress points for syllables is a killer for me.
But it is cute. I figured maybe I could get enough down to try and sub a manga - I heard Raze mention once that they're always looking for people and that it's a good way to learn. I'm not looking to learn to go out and speak it, but I do have a good photographic memory of what words are so it's easy for me to build a vocabulary. So who knows.
I'm just going to take the mainstream approach to learning Japanese and take a course (offered by the college). Maybe I'll pick it up at some point as a study aide/refresher.
Get an R4 ds cartridge and a micro sd card and you never have to worry about the cost of a game ever again =). I "have" the Japanese Coach, haven't tried it yet though.
I got it a while ago, and played it for a couple days, but then I was hit with so much extra projects that I haven't gotten a chance to get back to it.