This ability will not remove the Daze effect caused by running from mobs. However, this ability has been used to great effect against Hunters, Rogues, Paladins, and more who all have the ability to "daze" other players (especially against those whose use of it is critical to their strategy). Hand of Freedom will remove the effects of Player Daze, but is useless against Creature Daze.
In Warsong Gulch, when protecting the flag carrier, take note of the number of enemy priests or shaman around before casting Hand of Freedom. They can easily dispel it. Also, a level 70 mage can spellsteal it.
Patch 3.3.0 (08-Dec-2009): It is no longer possible to use this ability while under the effects of the druid spell Cyclone. In addition, disconnecting while rooted will no longer sometimes trigger casting this on oneself.
Patch 3.2.2 (2009-09-22): This ability now correctly removes the snaring component of Infected Wounds and Frostfire Bolt.
Patch 3.1.2 (2009-05-19): The base duration of this buff has been reduced from 10 seconds to 6 seconds.
Patch 3.0.8 (2009-01-20): Now works properly against the froststorm Breath Hunter pet ability.