I tried one years ago. They hide the gun well, and draw well if you learn to fight the shirttail or coat covering it.
Trouble is, somebody says, "hey, jump in the car and let's go....."
If he didn't know you're packin before, he knows now, or you ride in a VERY uncomfortable position.
Inside, working a counter, I always kept a J frame in my right rear pocket. Sitting on a stool was no problem.
Another good place is Mexican style under your shirt, with the tail out.