It's an alright game.
Despite it's in Japanese language, it's simple to understand if you know the basic rules of baseball (plus there are no opening scenes that drone on and on with that squiggly jap text).
I've found swinging the bat difficult, but pitching is just a quick swipe of the stylus down the touch screen.
Unlike Wii Sports baseball, you can attempt to get someone out by throwing it at a base (simple tap the icon of a base you want to throw to).
Definately some fun, and I don't think you're going to get a much better baseball game on DS.
If you're bored, I recommend checking this game out