I'm really looking forward for the new PVP Honor System and the new Deamon hunter class.
As a Pvper at heart, eliminating the gear and making everyone have the same chance of winning, really makes WoW more competitive where skill matters the most, and on top of that, pvping with the new Demon hunter class will be a delight.
Most memorable moments probably were the countless wipes we had to endure, and by sheer willpower, culminate in that sweet feeling when we finally killed the boss. Hope that felling continues this expansion.