As a tank, you'll gain instant queues and access to content much faster than other classes. You'll often be completing your quests at the level they come available, where damage dealing classes tend to access them a lvl or two higher. As a result, it can be difficult to keep hate while leveling because of the level disparity. You'll find that running dungeons closer to the end of their level spectrum will make threat holding much easier. This will become even more true in 2.1 as you queue for dungeons and people are filling your slots via the random feature. You'll end up at the minimum level tanking with 3 people level synced to the highest that dungeon allows.
Bottom line, hang in there, if you enjoy the tank playstyle, the wait will be worth it as you'll have queue access to content much faster than damage dealing classes.
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WoW Blackhand-US-Date of Retirement: 9/21/2010... /Sigh
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Beta - Devaria Ariadne - Ultros - Pugilist