From what we understand, Mass Effect saved data will transfer to Mass Effect 2 in a unique way. At the demonstration for the game we attended recently at E3, the audience was told by the presenter that choosing to transfer Mass Effect data to Mass Effect 2 would allow players to “continue exactly” where the first game left them hanging, which seems lofty at best.
But “exactly” could mean the two things BioWare specifically mentioned: moral choices (choosing to kill Wrex, for example) and character abilities.
It’s good news on the character-centric moral choices front, however, I believe BioWare isn’t stressing any of the older characters anyway. Mass Effect 2 is about Commander Shepard recruiting new guys — the galaxy’s baddest dudes — in order to survive his suicide mission.