Spellsteal will cost a mage 21% of his mana, so I really doubt you will be see yourself being dispel-raped against any teams that only has a mage as a offensive dispeller. There's even a possibility that Blizzard makes it non-spellstealable.
Other than that, the current auras were too good. There should definitely be a choice between having to cast the curses in caster form or choosing to put up an aura on yourself depending on who you are playing against. Having a huuge aura covering the whole arena with no way to counter it was a reaaaally bad design.
Also.. Sad to see the auto attack mechanic gone. Been leveling as demo (lvl 89 currently) on my soon-to-reroll-char, and I am really loving the current auto attack mechanic. I think it was a nice pay off spending 6 fury per second in demon form to be able to auto attack the target. I think they should cover it by reducing the fury costs per second in demo form, or just removing it all together.
I think buffing doom is a terrible idea. Will make demonology warlocks far stronger on most encounters.