Generally speaking, you can expect your exposed aggregate to be comfortable to walk on. Of course, comfort is subjective. If you are installing exposed aggregate in an area that you expect frequent use by barefooted persons such as pool surrounds, particularly by children who may be more inclined to be bothered by the bumps of the exposed stones on the surface of the concrete, there are a couple of options to consider.
You may choose a lighter exposure of the aggregate. You may also enquire as to the properties of the different aggregates used to determine if some provide a smoother finish. As the stones used in the concrete as aggregate are natural products, each possess unique and defining characteristics.
Additionally, you may choose to have the area honed, meaning you can maintain the appearance of the exposed stone aggregates while grinding the aggregates to a smooth finish that is more comfortable under foot- just be sure to seal your concrete around your pool area for safety, as well as protecting your concrete.
Exposed aggregate concrete surfaces, just like standard concrete, can become hot to walk on when temperatures soar if in an area that receives full sun.