A Feral druid with most of the talents mentioned will hit each target for about 1400 damage on average and crit for up to 3600 with around 5,500 attack power.
Useful for farming multiple mobs that are a few levels lower than the caster and who will die quickly or to deal what can be some sizeable AOE damage to a group of PVP opponents.
Use of this ability should be carefully weighed in certain situations, especially in instances or raids, since it uses most of the druids's energy and doesn't generate combo points. This is a very good way to use up an Omen of Clarity proc.
Combine with Savage Roar and Berserk and a high crit chance to deal a very large amount of damage when in close quarters combat, especially useful in pvp.
Edit
Patch 3.2.0 (2009-08-04): Percent of weapon damage done reduced from 260% to 250%. 
