Ideally, the lines could be smoother. I'd recommend going over them a second time to smooth out the edges, cos they seem a bit jagged. Also avoid using the line tool on things like the guitar strings - it is, unfortunately, something that stands out pretty plainly. Going over them a second time could help with that, too, though. :)

However your colouring style, lighting, and shading are all quite well done, and present a very unique aspect. The shapes you use as well are also very unique, and serve as a style that you may want to explore in more drawings in the future. :)

:D