I don't use one. It presents weapon retention problems if you end up in a tussle (something which is very possible in a close confrontation). Concealment is also tough because if the jacket / vest / shirt swings open revealing the weapon, when you reach or wave, you are considered to be in a technical violation (in many states) of the concealed requirement of the CCW.
I have used them from time to time. Several problems, one was the concealment factor mentioned. Two, when you perspire (think Texas in July) you sweat directly into your firearm. Three, they just really are not very comfortable. They look cool, but that is about the only thing going for them.
I have to second what Albert has stated. When you draw, you get "sweep", same as with a cross-draw.
This is one of the main reasons law enforcment has pulled away from holsters of this type (as well as retention problems that BreakerM. pointed out).
I would stick to strong side hip carry. Good retention, and when you present, you go from holster to target without "sweeping" your muzzle across the whole area. It may take some getting used to if you don't CC often, but in the end, it's quicker and safer for you and the ppl around you.