Plus they don't reveal undead, dwemer bots or ummmm some other thing... maybe cliff racers. Brain fade.
Detect Dead shows undead... that's the point of it.. and if i'm right it also shows constructs, but i'm not sure... i never used it yet.
I just got this Shout last night, I have not used it yet. Been involved in some pitched battles, and it's pretty easy to find your enemy in those.
Well, it's certainly more useful to sneaky characters... but i think it can be useful to anyone while dungeon diving.. you can looks around and see how many enemies to expect. One of the best things about the shout is that it shows dwarven spiders in the pipes and draugr in the coffins, so there is no big surprise when entering a room

I also often use it when i have to find a person who i need to talk to in a quest (as i don't use markers). I go in the building and then use Aura Whisper to look around to see where are the people in the house