I leveled 2 of my characters this way. It's very efficient, if you're tank or healer. One level in 1-2 hours. If you've got DPS buddy who knows his work and you're tank, who knows his work, this will be very fast. The only downside is, there are only 5 dungeons and you must do randoms, because they award a lot of XP. So it's getting boring. Not that boring like questing, if you ask me.