The full release will just be some minor edits in the main story text wise, as well as some UI changes here and there- most of the changes are focusing through the free play story line, which I love as it is a direct continuation to one of the four main endings- with the three guys or single ,not counting Sterling's ending.
Basically, they add romances to certain recruitable character- such as Seth, Faust and Collin...I think Wiz too, that's it, far as I remember. They also add story to everyone else, for interaction, some of them have been released already, but are still glitchy- particularly Fausts- I can't right click without the game freaking out on me, so have to wait for the update, but that was only after completing Fausts' romance, which I think messes with the awards system, which is why things be messing, because it isn't coded in there yet or something.
What I'm really looking forward to, is that they continue the original romances too through the 'new' band, and I'm really excited for that. Not much to go on, other than getting with new people may lead to jealousy scenes from then, and maybe a 'story' ending to the sequel, though I think you can keep playing for as long as you want then.
It isn't shown as potential scenes in your scenes lists though, so I hope that's updated, because I'd really like to see Robin continue her relationship with her potential boy of choice (Emmeeeeetttt!!!!) because she really grows. (Not so much with Dallas, methinks)
But that will only be added to the game on final release, so we have to be sad and patient.
But the game has an update button, so you don't need to go scouring for it, at least, so yay?