I did electrolysis years ago for my unibrow. It worked quite nicely. It hurt a bit, IIRC, but not terrible. She put cream on afterwards to sooth it. I have a few hairs (like one or two) on my arch that are stubborn, but I never went back to do it until they were gone. No scarring... I can't really think of any cons, actually, except the price - which I hope has come down since I did it about 15yrs ago.
I use an epilator for my growing chin hairs. It works very well. They claim that it will eventually cause the hairs to stop growing. I don't know if I totally believe it, but I don't have THAT many hairs on my lip/chin area, so I'm not too worried. I don't have to do it that often (like every couple of months), thankfully... cuz, I will tell you - it hurts!! - especially the upper lip. If I had more growth there I'd probably consider electrolysis too.