Yeah I'm with you. We've had trouble conveying the experience in words. Once people try it, they get it, and that suggests that we need to reduce the friction in trying it.
Some answers to your specific questions - Yes it's free, and all you need is a guitar (any acoustic or electric is fine) and a computer that has a microphone built in. There's no special cables or microphone required.
Some answers to your specific questions - Yes it's free, and all you need is a guitar (any acoustic or electric is fine) and a computer that has a microphone built in. There's no special cables or microphone required.