It's sort of the ultimate version of the game.
You get the additional US/EURO levels, but the characters retain their superior Japanese voices. I believe you get every music track, so Dunny Boy Williamson Show (which is absent from the US/EURO version) is included as well as all the US exclusive tracks (Jurassic 5, Mix Master mike, Rob Zombie, etc) and the EURO exclusive tracks (Recipe for the Perfect Afro, etc.). The timer shows the milliseconds and you have more graffiti than the original Japanese version.
Still, if you have the US and original Japanese version, De La Jet Set Radio isn't a must own.