The total amount of footage shown is not more than 30 seconds, in about 5 or 6 chunks, so it's very brief, unfortunately. I'd have watched an hour of that very happily. The pop up spell selection is shown at one point, and it looks much more convenient than in D1. They display very low on the screen, rather than covering up so much of the action as in D1. When the cursor is over a spell icon, you get a litle pop up text box over the spell icon with the spell name, level, and a brief description of the spell's action.
Firewall is just graphically unbelievable.
It explodes on the point you cast it at, and burns highest there, while spreading out in both directions about 5 or 6 squares, getting lower as it spreads. The impression is that the center point would be the most damaging. It looks great in the demo, and they are on the bright desert surface, so imagine it in the dark of Act 1, or the lower levels of the dungeon. The death animations are all incredible. The Blunderbore dies with a bloody explosion of its chest and falls to the earth looking quite ruined and still very large.