I'm currently playing a hunter whose pet appears to be working fine, however i understand i may be in the minority.
The pet i'm currently using is a wolf i trained in Elwynn Forest outside of Goldshire, if that makes any difference.
When i initially obtained the pet he did not have growl or claw available. However, opening the spellbook to the general tab and going to beast training opens the menu for spending your pet's "talent" points, growl and claw were available free and immediately to me. I had not seen any mention of doing this in the thread so far so i thought it might be worth a mention.
He growls, holds aggro, attacks and returns as i command. That said i am having a problem with my pet bar disappearing randomly, requiring me to dismiss then resummon my pet to get it to reappear however i've been attributing that to my bartender addon rather than an issue with the server, since i've found display bugs to be generally client side, especially when addons and a scripting engine are involved and i had not disabled it to see if the default UI was doing the same thing.