Upgrading from a smaller shoulder bag, to this larger one has been fantastic. Smaller strapped bags cause some stress on my shoulder when carrying water, whereas this Sling comes with a much larger strap. You can shorten it and carry it like a normal bag.
With the larger strap, when carrying heavy items, it actually lines the bag up really well across the middle of my back. Meaning it doesn't weigh down on my shoulders, or feel uncomfortable.
Overall, there is a lot of room - can regularly carry my keys, extra stuff from pockets, full water bottle, small umbrella, etc.
Great purchase, highly recommend.