Okay, after playing through a bit of the Rebirth Update, the best way I can describe it is:
It added CG that should have probably been in the base game. Also, the individual routes also have a few more dialogues. Game kinda felt unfinished so I guess they finally finished the game
The dialogue and choices are still largely the same, and the NSFW stuff still isn't animated, all static CGS mostly. BUT, at least the harem ending has 2-3 more CGs rather than just the original 1. Probably not worth replaying unless you really really liked one of the characters and wish they had more dialogue, but chances are, that's not the case.
I'll put a full save here, it goes into ` C:\Users\"Your_user"\AppData\LocalLow\Myosuki\Girls! Girls! Girls!\NaninovelData\
Saves `
Also you ABSOLUTELY STILL NEED A WALKTHROUGH for this game the update doesn't change that:
You must be registered to see the links
(All Endings except Hayasaka, pre-update)
You must be registered to see the links
(Guide for Hayasaka, Rebirth update)