One of the cleanest pieces of fan art I've seen so far. The thin line quality choice makes Roshi really aesthetically pleasing and clean, and you can clearly see his robotic details like the joints and the subtle edges in his boots and fingers. The geometry is also really clean. The color choice is also faithful to Yoshi's and provides excellent contrast between his boots, belly, and hands, and allows you to see and navigate through his different parts. His pose is great too, with his expressive hands, silhouette, and the sense of depth. I guess the only possible complaint you could lodge is the lack of shading, but the sense of dimension and shapes without are done so well that may not be necessary. Artwork like this is a lot more challenging to make than it seems, and are the pieces you aspire to make as a robot artist. :)