The one thing that I notice immediately is that you will always have a clip showing on your pocket. I don't even like to carry a pocket knife that way because the clip can be seen. Also, the magazine doesn't seem very snug in the sleeve - it could slip out. (Probably won't, since it is in your pocket, but it could.) Finally, only the bottom of the magazine is covered - I wonder why they didn't make the sleeve taller? It would have covered the entire magazine - the magazine would have better protection from lint getting in.
The best thing about this magazine holder is that you can quickly access your magazine; you don't have to remove the cover, because the cover is clipped onto your pocket - it will stay behind when you grab the magazine. Also, the magazine is always perfectly positioned for grabbing it and inserting it into your gun.
The visible clip is what I don't want. However, with my shirt tail out, the clip would be concealed.
This one is $55, while Ammo Armor is $10. Big difference!
It is good to know about an option other than Ammo Armor. I'm glad that products like this are finally becoming available.