Good colors and well composed. I like how the detail in his guitar is visible in the shadow from his arm.
Strikes me as a dennisheckman style photo, but I don't think it's his because it's not sleeveless shirt weather in Colorado right now.
Nice image. I like how everything in this photograph, from the dirt on his cap to the condition of his guitar, tells me that life has not been easy for this guy. I bet this would also look good in black and white.