I see a problem getting them out of the pouch in a timely manner. It seems like they're probably pretty snug in there, and you don't really have anything to grab quickly.
And, you probably paid as much for it as a proper mag pouch would have cost, even a cheap one. In my experience the cell phone holsters don't last very long, they're cheaply built.
Is there a reason you don't like typical mag pouches? I find they're comfortable, they don't take up much real estate, and they're quick to grab.