The buckshot version of this cartridge has plenty of power for self-defense.
The main drawback to this ammo is the reliability of feeding. Most pump actions have issues feeding them. In fact, according to Aguila, just about every pump gun other than the Winchester 1300 Defender and Winchester 97 will need to have a gunsmith work on them, in order to feed these cartridges reliably.
See:
http://www.aguilaammo.com/minishells_shotgun_mods.htm