Photoshop brushes.. how do you take advantage of them

Ive been a photoshop user for liek 8 years now. I totally understand how you can take advantage of illustrator brushes. But I just dont see what the big deal is with photoshop brushes. Why is everyone crazy about them? Ok I find them useful with the eraser tool (actually) , but how do you take advantage of these brushes with the brush tool? Can you give me an example? in the case of abstract brushes, and real life object brushes

Thanks!