I don't have any personal experience, but I have researched them some. I do not recall reading anything bad about them, but I have read many good things.
I can't attest to the quality of their holsters; however, their archery quivers are A+ top-notch items. With that in mind, I wouldn't hesitate buying a Fist holster if it suits your specific needs.
Tucker makes a great IWB, and mika also makes a great pocket holster.
Just a couple more to look at, I know there are lots of holsters manufactures.
These two are good brands. You just try to eliminate buying the ones that are going to end up sitting on the shelf.
The only Fist holster I have purchased was a #12 for a Smith J frame. It was for my son-in-law for Christmas, and I did not have time to wait several months. I received it probably within 4-6 weeks, and maybe less.
I was well pleased with it, and if I didn't have a J-Frame holster on order from Alessi I would get another #12 for my own J-Frames. I like the muzzle to clear the holster by the time it gets to the top of the belt. The #12 for the J-Frame is designed that way, but others seem to ride a little higher.
If you like the design, it is my opinion that the quality will be very satisfactory. I do own holsters by some of the absolute top makers.
I ordered the #4 Fist and like it but find it rides too low. It conceals better but is difficult to draw from. It's a tossup but I think I prefer to be able to draw easier.
I have about 9 Fist Holsters and love them! My favorite is the #K1. that is the model I have for all my guns that I carry. I only use IWB. Make sure you have a gun belt!