A few random thoughts
I loved Afterimage even more than the previous one. The characters are much more well developed, and there is a right balance between action, angst, love and lighter moments.
Boyd: I had so many change of heart about him.. I hated him, I took pity on him, I hated him again, I loved him.
Hsin: I had to stop reading so many times, 'cause my mind wandered about him, about what I would have done in order to help him (ok, this sounds weird...)
So.. once again, highly recommended and once again, caution: it causes severe addiction.