Sometimes, though, it's annoying rather than useful. I've acted hastily and hearthed from Un'Goro Crater to Stormwind a couple of times -- the repeat journey isn't something to be casually undertaken. Fortunately, several classes -- as well as engineers -- have tricks to help with travel, from the Shaman's Astral Recall to the Druid's Teleport: Moonglade.
Where is your hearthstone set? Have you found an efficient way of getting around that relies on these travel tricks to work? My druid is parked in Stormwind, as Moonglade gives her access to Kalimdor, although the flight from Moonglade to Gadgetzan or Silithus is still a long one. On some of my lower characters, I've forgotten to set the hearthstone at all -- I managed to run a level 10 dwarf to Darkshore, but left the hearthstone near Anvilmar. Oops!