WoW's dungeon content doesn't even start until 20 (alliance) or 15 (horde). Those levels are just for getting to know how to play your character without ending up killing yourself. Once you play another character, you'll end up finishing the level 5-ish quests in =< 2 minutes.
The REAL content doesn't start until high-40's. The GREAT content doesn't start until after 60 (you get 60, then attuned for MC and keyed for Onyxia, etc).