Scrolling back in time with the mouse wheel sounds convenient. I'll have to try that out next time!
Mostly the writing. Even if you just got rid of the dialogue that is just "..." I think that would make the game flow better. The ideal goal is to make every dialogue exchange unique.
It would be cool if the audio was different for each sentence, but that would take considerable time, effort and creativity. When Gregory talks it almost sounded like a Minion language. :)