I love the fact this is just line art and that you used white/black to shade what I presume to be metal/leather. You also kept to the lighting which makes this piece even better! The abs are fine but maybe add a thicker line for where the skin folds, this also goes for the rest of chest, I think it shall add a little bit more depth to the piece. The clothes are very original! I also do love the little tattoo, and I do love the detail you put into your images. Keep it up! I do have a couple more things to advise; I feel that the top of the arms and shoulders are too thin compare to the musculature of his chest/abdomen, maybe just thicken up a bit and show a bit of muscle? I also think that the lines on the robe/skirt are too thick, maybe show a few creases that way you can do thick and thin lines? All-in-all a lovely piece of work!