That was the first caller I purchased. It works fine. I think it is more the skill of the person using the caller. Since then, I have purchased a couple of others from Crowmart. They work even better than the hammerin caller but it is nice to have a few different ones since crows all have different voices.
I have used the Hammerin Crow call before and its ok but its a start. Its hard to make the natural sounds of the crow such as the Rally call or some of the other sounds thats crows make. If you get into crow hunting a lot I would buy a gibson crow call, Faulks C-50, and the Knight and Hale crow call. They sound very good. Depending on your location will dictate how many crows may respond to you. Just be sure to get by some of the lowest trees in the area and stay well concealed with lil movement till shooting time.