Not an expert, but looks like a really bad idea to me.
Requires two hands to unholster - same drawbacks there as carrying with none in the chamber. What if weak hand is busy fending off mugger, or holding a kid?
Also looks difficult to draw in certain positions. You have to drag the pistol under your belt... not going to work well for some body types or if you wear your belt snug.
Appears to take more time... you have to draw twice... draw the holster with your weak hand then draw the weapon with your strong hand.
Xzibit would be proud. "Yo dawg, I heard you like to draw, so I holstered your holster so now you can draw before you draw."
However, this thing seems to be a really bad idea. I wonder how many they actually sell, and what percentage of purchasers actually ends up using them?
A piece of garbage that is no better than a widow maker over the top flap holster worn on old school dress uniform belts.
Never use a holster that requires a 2 handed draw.