I actually purchased two of these bags - one for me and one for my son. With summer quickly approaching, there are many day trips and longer trips planned.
Unfortunately, my son is required to have an epi-pen and some other medications with him at all times. He also insists on having his tablet and I insist on an actual book. At 9 years old, he is being given more and more freedom. Because of this, I had to find a bag he was comfortable wearing and would carry everything he needed and wanted.
After seeing how wonderful the bag was for him, I realized it was a great size for me too. Since he is now carrying his own stuff, I am able to carry fewer things. I also realized I didn't use the majority of things I felt I needed at all times.
Once I realized that, it became apparent that this bag was more than big enough for me. We both love that it is adjustable, we are able to make it comfortable for each of us with a simple adjustment.
The padding on the strap also helps to make it very comfortable. And, by being a sling bag where the bag part is on your back, you don't have to worry about it swinging around as long as you have it tight enough. No matter how active you are or what you are doing, it stay put and out of the way.