I've only played the DS remake, so I can't tell you the differences firsthand, but going by what I've found online, they did include more of the script, Namingway has many different purposes, the voice acting is new (obviously), and Whyt is stylus-controlled only. I don't think there are any new dungeons or eidolons or anything like that, though. And, just as an assumption, the characters' thoughts on the menu weren't there previously?
They did fix the character revivals issue, though. Now, they use augments, which give the characters you have at the time abilities of old characters in the past. It sounds a lot better to me~
I've enjoyed playing the DS version. Don't shoot me. D: