I started using My Japanese Coach on the DS, but haven't touched it in a few months. I've probably forgotten everything I learned in it.
How good is something like that? I assume it's not quite the full learning experience and more of an accessory or lead in to deeper learning, but it would be handy.
It's helpful as a framework, definitely, and it's great in pounding in basic vocabulary. I didn't get far enough to evaluate beyond that. I do know that there is a Japanese DS cart that was very popular for kanji identification, but I never picked it up. Half the other foreign teachers I knew had it, though.
Edit: Kanji Sonomama Rakubiki Jiten (helpful once you learn basic stroke order, which I've completely forgotten.)