Amanda Rivera pointed out that hunters have lost their ability to double, or even triple, trap, and although many hunters were not using this exploit, a large proportion were. Even though this might be a fair fix, I imagine that for many hunters, the raids they have "on farm" will suddenly be much more confusing.
As Robin reported earlier, hunters can no longer use feign death on a boss fight in order to be removed from combat (you can still drop aggro) and go have a drink. Officially, this is a bug fix, and in fact, many hunters had not even realized that they could go take a swig during a boss encounter. Unfortunately, this is not just impacting a Hunter's ability to pump up their mana pool; it's also affecting their ability to feed their pets.
It is being reported that pets are losing happiness at a faster rate post-patch, and that while raiding, because a hunter can no longer feign death and feed their pet, the prospect of using their pet while raiding, or achieving maximum benefit from doing so, is looking somewhat grim for many.