Wow, this is an amazing piece (I would have said painting if you hadn't specified illustration). The colors, contrast, and shading are perfect, as is the symmetry of the face and collar bone. Love the hair and the overall beauty of the woman. My only constructive criticism (and it really is a small point) is that it seems unnecessary to put her in a lacy bra. That is to say that she is already beautiful, even sexy, without needing to be sexuallized via lingerie. Side note: was she originally painted nude? It kind of looks like it was originally a topless portrait, with the bra and quote added later.