One of the better Pokemon games!
Pokemon Gold and Silver are both awesome games with Crystal being a little better than both of Silver and Gold. This game is fairly quick moving, easy to navigate the world map, a great amount of Pokemon (not too little, not too many), good story line, and features many upgrades from Red and Green.
I would say knowing Japanese is recommended, but not necessary with the exception of a few words like yes, no, and save.
You start off in Johto (west of Kanto) and go against the 8 eight gym leaders of the Johto region. It usually takes me about 7-8 hours to do so. Since I used only 1 Pokemon, Feraligatr, the whole time, the game moves very fast. Afterwards, you journey to Kanto to face the Elite 4. Afterwards, you get to explore a slightly modified version of Kanto. The highlight of Silver version is the battle with Lugia. You travel to the whirl islands and navigate your way through the dark maze to fight Lugia and catch it. You also get to meet a stronger Ho-Oh after collecting the Rainbow Wing. After you are done with everything, you can journey to a mountain region where you face the final challenge of the game!
As far as differences between the US and Japanese versions, I haven't noticed anything.
Great game, fair amount of gameplay time, good storyline, and for $20, a great deal!
