http://www.dailytech.com/Lucas+Make...rticle22623.htm

Among the biggest ones, reportedly:

The Yoda puppet is replaced in all scenes (including on Dagobah and Yoda's spirit on Endor) with the CGI Yoda scene in the latter two films of the prequel trilogy at least one of the prequel films, with some sources saying the replacement will be applied to the original trilogy as well (unconfirmed). [video]
Darth Vader is no longer silent when Emperor Palpatine is electrocuting Luke with force lightning. He gives what at first sounds like a quizzical "Noooo?" and then follows with a louder "NOOOOOO!!!" à la his response when he found out Padmé died in Star Wars Episode III: Revenge of the Sith (confirmed). [video]
Obi-Wan's Krayt Dragon howl, which scares off the sand people on Tatooine has been altered, which according to The Superficial "sounds like a pedophile getting his dick caught in a screen door" (unconfirmed). [video]
The Han Solo and Greedo shootout has been sped up (Greedo still shoots first, as with the previous edit) (unconfirmed). [video]
Wicket the Ewok's eyes are now CGI animated and blink with big "lucious" eyelashes (unconfirmed).
Han Solo now emits brilliant CGI lighting effects when he is unfrozen from his carbonite nap (unconfirmed).
Jabba the Hutt's palace has a fancy new rendered door (unconfirmed). [video]
Extra CGI TIE-Fighters and TIE-Interceptors appear out of nowhere (due to shoddy CGI) in the Death Star II battle (unconfirmed). [video]
Lightsaber colors have been fixed to correspond with the original theatrical versions (about the only change that reverts previous ones) (unconfirmed). [video]

(All of these rumors have been widely reported in multiple sources, including the Associated Press, for a number of the unconfirmed rumors.)

簡單說就是許多橋段要用CG從新繪製, 部分台詞會改變.
感覺就是一整個謀殺經典呀, 希望不會變得像金大師的第三版一樣.