Sadly, I'm pretty late to the party, but I'll share what I use it for. Please stop reading if you're not over 18.
I have software that monitors heart-rate and skin temperature. It also drives a few vibrators.
I tie my spouse to the bed, attach the heart rate monitor and skin temp gauge, and place the vibrators in sensitive spots and then execute my program(s).
I have a T&D program. It brings her very close to orgasm, then stops, or slows so she doesn't climax, then restarts when her heart rate drops below a certain point. It's pretty good at edging her.
I have a FO program that makes her climax repeatedly, increasing the intensity until it maxes out (and she almost passes out.)
I have a pure tease program that just makes her really horny without doing any edging.
These programs are specific to her. We ran many scenes where I just recorded the sensors against self-reported levels of arousal so I could tailor the program to bring her to specific heights of arousal. It works pretty well. When she's tied and in a T&D scenario, she gets quite desperate to climax. The arousal program works well to get her to the aggressive-horny stage. We're still working on the FO program. The vibrators I have aren't strong enough to keep her climaxing after the first few.
Anyway, that's how I use my PI.