Remember life without DKP? No raid schedules. No guildchat, no PvP or reputation grinds. Imagine, instead, the sheer unadulterated joy of discovering new lands, exploring a new class, and treading entirely new territory. Taking my first tentative steps into Silvermoon City, I found a familiar feeling coming back to me -- the same feeling I had when, on my very first character, I ventured into Darnassus. A mixture of amazement at the beautiful surroundings, excitement at the places yet to explore and quests yet to uncover, and pleasure in being lost.
Wandering into a building with no idea what's inside and being surprised; questlines and clever items that hook right into the Blood Elves' magic-based storyline; a gorgeous landscape in glorious technicolour with a distinctly new feel. All of these, and more, are sufficient drivers to make levelling a novel and exciting process, despite the same "kill ten"/"deliver this"-style quests we've done to death.
Starting a new character is a fresh experience again, especially for those of us who have exhausted the existing newbie areas. However, it strikes me that venturing from this magical fantasyland back into the "real" world at level 20 will feel very strange; the downside of adding new content at either end of the levelling curve, but not in the middle.