There is no point in running them. Except for the two beginning ones, they are long and the loot and XP are no better than what can be obtained by questing. This holds double true for HM FP's. The content is cool and challenging but my time is better spent doing something else.
This. The reward for the time invested is not worth it, not even close. Its helpful for breaking up the grind but that's it. I'd rather pvp because I know if I pvp enough by the time I get to 20 and 40 I have a shiny new set of blues. And then by the time I get to 50 I can get a head start on 50 gear.