To figure out what this game might be like, I've looked at everything available to us.
Check out everything on the Ratcatcher's Tale site. Read the Daily Altdorfers and the story about Rolf.
Then look over the WFRP3 promo and description pages. Look at all of the cards, dice and other images very closely -- even the flash animations at the top of the page. Look at the photos that people have taken at GenCon showing the materials and mock-ups.
Watch the FFG highlights from GenCon. Read the WFRP3 Facts thread stickied at the top of the forum.
If you're familiar with V1 or V2, you're going to see a lot of similar terms and game structure going into WFRP3. While it looks like V3 is a big step away from V2, I don't think it's nearly as big as it appears now.
But you might have to look at all of the 'evidence' together to really get a sense of what the game might be like. I'm sure I'll go back and squint at the images some more, and I'll figure something else out.* After looking closely at everything, I'm very much looking forward to playing it.
*Today I've been looking at the green and red 'puzzle pieces' that appear on the Troll Slayer career card. I'm pretty sure that they correspond to the stances -- red for Reckless, green for Conservative. Those are probably indicating your card slots for action cards, which we now know are 2-sided -- conservative on one side, reckless on the other. So the Ranged Shot card probably has a red reckless side as well as a green conservative side. The differences are almost certainly going to be the kinds of results you can achieve by different combinations of dice-symbols.