I've had the D3 beta access for several months now, and experienced the old and new systems they were using. I know you're going to love it - it's got all the classic Diablo smash-kill-loot goodness and really great classes.
That being said, (and I know you're not going to understand unless you've played the beta/demo...) the amount of content actually IN the beta to play is so minuscule as to not be something to be jealous of or think you're missing anything. I can take a brand-new level 1 character all the way through it in about 1/2 hour, and a level 13 (max beta level) char through in about 4 minutes - and that is just solving the random maze of the levels you have to get through! It really is just a sliver of the content of the actual game and while you get quickly overpowered for the content that you're plowing through, the actual game is going to smash face and be awesome.
I have no inside information (they don't share squat with us "testers"), but I'm pretty certain the release date announcement will be here very soon. I can't wait to play the full game!
-Mike