It is believed that this ability reduces fall damage by 30%. This is as yet unconfirmed.
This ability also increases the distance the Druid can fall before taking damage. Since any damage removes stealth, this is useful for sneaking into places that would otherwise leave the Druid vulnerable.
Cheetahs may be feline, but they're as graceful as a brick. This ability doesn't apply to them.
Tips and tactics
Be sure to shift into Cat Form during or before those long falls.