The Detroit has been made since, what.. the beginning of time? It's been used in big rigs, back hoes, and other commercial equipment for years. I would venture to say that it's one of, if not the strongest/most reliable locker out there.
However, on the road you will notice it's there. Getting on and off the gas will sometimes try and make it change lanes with you. A little corrective steering takes care of that though. You get used to it very quickly. It's less obvious in a auto than an manual trans, I've heard, and it's a little smoother than a lunchbox locker.
Sometimes (about once every couple weeks for me) it'll make a loud metalic "Bang!" sound, that everyone around you can hear. People will think you broke something.
Edit: Ran it for about a year now. Sorta regret not getting a selectable. Kinda annoying if you have to drive it everyday. Performs flawlessly offroad though.