I have put in several of them.
In new resi, there are unually no problems if it is wired correctly(no shared neutrals). I had to troubleshoot my own wiring once. Took me several hours(up and down the stairs to reset the breaker)until I finally found a shared neutral in a switch box. I learned that lesson. More of a problem is just bad breakers. I will put power on the house and they won't hold. I replace it and everything is good.
The bigger problem is remodels and additions. You can't just find a hot in the attic or crawl somewhere and tap on because you don't know how its wired.
The last issue is panel space. With the 08 code, you can end up with several afci breakers in the panel. They are not small but rather crowd into the neutral and ground bars.
I don't have any real horror stories, just a bunch of "Ahh Crap" stories.
