Pretty good; would be better if the third installment ever came out, but that seems unlikely to happen. Still, it is well thought out and offers a great, but incomplete, starting point for anyone wanting to create their own d20 sci-fi setting.
One word: Awesome. I love the Sailing the Sea of Stars products. Their earlier release on what elements to include in a space opera game was very useful to me when I was putting together my space campaign. With this product, I have some great items to base my own creations around, and some VERY useful stuff that I barely needed to modify to put right into my game. I can't say enough.