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That depends on who you talk to.. IMO
I find them great, inexpensive, which is not because they're cheap, but simple designs made for either IWB or OWB, clip-ons, in most cases, and I'm a slim guy.
I like them for several reasons. Ease of putting on, anywhere one wants to carry, otherwise, versatility. Ease of drawing out, yet stay snug against one's body IWB. No break-in, very natural feeling, they don't make you sweat, nor does one's sweet get into a exposed muzzle, being closed - ended, if one is using one of their IWB holsters.
Very convenient to keep guns in, without ever getting any holster wear on ones guns, along with protecting them from scratches laying them down on tables, desk, etc., along with protecting them from other guns, holstered in any of the various sizes of IWB clip-ons, while storing them in a safe, from scratching each other or being scratched by a safe wall itself.
To each his own, as some of UM's holsters work well for some, and some don't.
I just know that none of mine have ever failed in any areas I spoke of, including actual CCW wear and use, and I'm slim, but they don't make any of my guns paint, and most of the time I have on either a T shirt, or a Hawaiian shirt, only, with Levis.
I do have a nice gun belt, which does help in holding the holstered gun tight, and in what ever semi cant position I use for the moment without either holster or gun moving around, as I do.
LS