EDIT: See part two here
...as Idolm@ster: Dearly Stars, some kind of a side story to The Idolm@ster (well... not as if The Idolm@ster has any storyline).
So no Haruka, no Yayoi, no Chihaya, no Azusa, no Iori etc for you, not in your control.
And don't expect it to have 3D either. Since certain dancing games on the DS have proved that DS is total crap when it comes to rendering a character. In comparison, the PSP is... half crap. At least half is better than none.
So no concerts either.
Well wtf. What's Idolm@ster without the concerts. It'd be like a pussy breeding type game for girls.
Although I love Idolm@ster alot, I have a feeling that this thing is doomed to failure. The Idolm@ster SP is already a highly cut-down version with limited clothing and song choices and pretty bad graphics. Now how much can you fit into a DS cartridge.