The thing I'm looking most forward to is the class mechanics. As an owner of 6 level 80s as of this writing, I want to see how different each class plays on the leveling and endgame stages. From what I've heard so far from previews, leveling is being completely revamped (you get a free ability by choosing your spec at level 10, for example), and the endgame is going to be practically like Ulduar, which was an instance that was acclaimed by many to be one of the best in Wrath of the Lich King, due to its slight digression back to archaic design, in addition to being vast.
The biggest thing though, as I main a hunter, is the mana to focus change. Too long have I seen the "Not enough mana" message on the screen. I feel like I'm playing my Arcane Mage as a Marksmanship Hunter for god's sake. I also noticed they've added "Venoms" to replace all but Serpent Sting. This system makes it harder to cleanse the hunter's poisons and I would really like to see how it works out, especially now that Marksmanship will have a self-healing tool.
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Interest of Wowhead (Yes I forgot to put in a sig, so this'll work as a placeholder for now)
Edited, Jul 27th 2010 2:09am by interest