I'm a huge fan of both Mara Jade and Thrawn (and Pellaeon too, who also gets a cameo), so I was excited to see more of them. Zahn is one of my favorite Star Wars authors, and Choices of One is another solid Star Wars novel.
Given the time period of the novel, I went in expecting that certain characters wouldn't be able to meet at all, and I was pleasantly surprised by their interaction. I was especially amused by Luke in his dorky farmboy stage and seeing Mara as the deadly efficient -but merciful - Emperor's Hand is always a treat.
I also like how this book had me rooting both for the Rebels and the Empire (or at least some Imperials) at the same time. It's nice to see the Empire as individuals, good and bad.