Good question, otherwise what would be the point?

The main things you will see on launch are:

Even faster betting than before
Multi currency support - play and invest
"App" support - casino account and bankroll service so you can create your own casino using our platform.
Investment feature making a return
Free bets to test before deposit
New simpler and easier to use theme (in my oppinion)

However that's just the main differences on initial launch.

There's things that you won't see since they are either behind the scenes or will be released incrementally after launch.
The whole site has been rewritten from scratch with scalability and maintanability in mind.

This allows adding:
new games,
native mobile app support,
bonus and reward systems,
and better promotions to be added easily.

I won't go in to the future additions much here until after the improved dice site is launched