Like others have said nothing wrong with it. Just not for me, if i have to carry more things that i can fit in my pockets it either gets stashed in my car or i grab a backpack.
For me there is no need to carry my charger with me, it stays in the car (usually have two sets of charger anyways, one that just stays in the car and one for the house, besides i hook up my phone to the car to listen to music etc. so its usually charged anyways by the time i get to places.
Especially the one from Amazon looks more like a Camera back, if anything you look like a tourist if you are even noticed.