So far Tank seems pretty easy to me.
Then again I main Monk and know the encounters already which drasticly reduces the learning curve and being a melee main helps with the knowledge of placing the mobs just right for the DPS to do their jobs properly.
Holding aggro became very easy since they buffed Defiance and Shield Oath too.
I'd say the trickiest part is learning the encounter and knowing when to use which Cooldown, but than again every class has to go through that.
Other than that tanking is really fun and relaxing.