Mini, I agree, is pretty useful at times. Grand Dragons and Chimeras are vulnerable to it, so it can really help. Unfortunately, it's seriously let down by the sheer likelihood of missing the target. In order to inflict white-magic status changes reliably, I perfer to use one of Zidane's abilities, Soul Blade I believe. Depending on which sword he's carrying, this ability can inflict Mini, Petrify, Silence, Darkness or many other abnormalities with near total accuracy.