Everything you would ever want to know about this ability:
-Works on you & your pet.
-Can't be used while in combat, but feigning to drop combat & then casting camo immediately works.
-While standing still, you are stealthed, meaning no one outside your party can see you
until they're very close.
-While moving you are, well, camouflaged. People can see you but can't attack you with anything except melee attacks.
-Stealthers can't use any of their stealth-only abilities on you; they have to pop out of stealth to attack you.
-Any damage taken by you, including AOE abilities like Flamestrike, Frost Nova, etc, breaks your camouflage.
-Your pet taking damage, but not you, does NOT break your camouflage.
-Camo is broken when arena games start; you have to use camo AFTER the gates open.
-Laying traps, swapping aspects, using mend pet, reviving your pet, using pet abilities (not attacks), & eating food do NOT break camo.
-Using any attack, dismissing pets & calling new pets DOES break camo.
-Sending your pet to attack breaks camo immediately, even before your pet engages.
Basically, this is an upgraded version of stealth with a 1-minute cooldown. In PvE, you can use it to get into position before the fight and start DPS as soon as the tank pulls. In PvP, you can use it to start off any fight any way you want.
Because rogues & ferals can't use any openers on you, you no longer need to camp flare @ the start of an arena match; you can use the flare offensively to try and knock them out while you waltz over to the other team's healer,
unable to be attacked until you open.
I think this is a really underrated ability. While it's not something you can use all the time, and it definitely doesn't make hunters a stealth class, you can still use it to get a unique advantage over other players. Plus it means you don't have to go night elf to be invisible, which is sweet, because night elves suck.