I actually just finished Android's Dream! I really enjoyed that book, though I went in to it thinking it was part of the Old Man's War books, so was a bit confused initially. The ending was spot on, though. :)
I'm currently reading Zoe's Tale. Not as strong of a start as Android's Dream but still seems promising to me. Once I'm done with this, and David Weber's By Heresies Distressed, I'll be sure to check out Agent to the Stars.