Tried this as I find a running belt too small for my Iphone and rubs on a long run. This bag has plenty of room for an Iphone 7, gels, keys, tissues etc, without rubbing or weighing you down too much. Could probably fit a small bottle of water too. Good that you can wear it wear it on your back or on your chest for easy access. Would have liked to be able to tighten the straps a bit more (I'm quite small) but not a major problem. Very good value for the price.
the bag is good because it's possible to carry more than you phone, I have 2 phones I needed something better than the armband. Also it's possible to carry my keys and still be some space left.
For me the only issue is that it could be a little bit bigger, but besides that it's a good purchase.