Skill? Really? I learned in about two hours how to use plain old picks well enough to open my Kwikset front door lock in 15 minutes. From everything I read, the gun is much simpler to use.
It's a skill I've never managed to crack (perhaps in part down to my very unsteady hands). From what I've read, a lot of people buy pick guns expecting them to be a one-button solution, and are disappointed to find they can't open locks with them without training and practice.