I watched about 2hrs last night. There are a ton of new scenes, I am going to defer to tinsel since he quotes the godfather a lot but I think the scene where young Don corleone (deniro) meets a young hymen Roth and helps him change his name is new.

There's also a scene from 1 where don, sonny, michael, Fredo, and Johnny Fontaine go to see their old lawyer on his deathbed right after the wedding scene. I know that one is new because the original cuts from the wedding to Tom hagen going to LA to cut off a Horsehead.