Here is a story found at Endless Nocturne, a great site devoted to Eternal Sonata.
http://www.endlessnocturne.com/index.html
New Eternal Sonata details, still 360 exclusive
Posted Aug 17th 2007 5:35PM by Richard Mitchell
Filed under: News
During an Eternal Sonata conference call last night, we managed to clarify some details on the game and even uncover some new details. First of all, we learned that the game should take about 30 hours to complete for players that wish to simply charge through. If, however, you wish to complete all the side-quests (and you won't get the full story if you don't), it will take much longer. In fact, some of the side-quests aren't even accessible on the first play-through, so players will have at least some incentive to go through the game more than once. RPG fans hoping for some downloadable goodness on par with Blue Dragon will likely be disappointed to hear that very little is planned at this point. In fact, the only DLC planned right now is actually an unlock key to listen to music from the game. What's more, this content is unlockable in the game itself, so the DLC is basically moot. On a more positive note the game will contain both English and Japanese voice tracks, so purists won't have to cover their ears.
On the gameplay side of things, we did learn that there are a total of 10 playable characters in the game, though you can only have three in your party at any given time. Furthermore, not every character will be available at all points in the game. Also, the game has a multiplayer feature of sorts. While not a true multiplayer mode, you can control each party member with a different controller during battles, so you can let your friends get in on at least some of the action.
Finally, Eternal Sonata is still planned as an Xbox 360 exclusive at this point in time. So, if you want get down with Chopin's fever dream fantasy, you can only do it on 360 (for now anyway). Eternal Sonata is due to arrive next month.