I was surprised to find this out, and thought I'd share just in case others also hadn't heard - that pretty much in WoD:
You should never use warlock healthstones.
Health pots (now called Healing Tonic) no longer share a cooldown with dps/mana potions, but instead share a cooldown with Healthstones (and Shieldtronic Shields - more about these later...). They're also extremely easy to make (and cheap to buy from the AH). Since they heal for quite a bit more than the lock stones, it turns out that these are what we should be using - who knew?
Well these are kinda neat, they don't 'heal' for as much as the Tonics, but they do act as an absorb instead of a true heal. So, for cases when a big hit is coming in that might kill you, this shield might actually be preferred.