For me, a 3-star review means "...when you read it to the end, put it down and proceed to forget all about it in the next instant."
Sadly, this book was a whimper of an end for me out of the series. Over the course of this series, I increasingly felt like the books were filling pages with barely average stuff, and I ceased to care. The book simply failed to make me care about the story or characters, and didn't hold excitement.
In this final installment, the crew of the Athena forms an alliance with the Boxans and various added species to try to end the scourge of the Xiingans. Athena the ship/AI continues to get smarter, humans continue to act slightly dumb, and other aliens are do predictable and uninteresting things in this ultimate battle - like move ships around, launch nuclear warhead bombs, get ships blown up, blow ships up, punch thru space using wormholes, and general win or lose.
A solution to the Xiingin influence appears virtually out of nowhere, and works with no false starts. Enemies of the Xiingin can now dispatch important Xiingin with a 1-page-long fight, after having lost similar fights for 5 previous books. The problem of how to disable the Star Shield is discovered with the experiment of an idea or two (without real explanation of solution). Emotional linkages between characters are uninspired, and unemotional.
Yawn.
By about 20% into this installment, I found myself skimming entire pages, and scrolling to the next, hoping I would recognize an interesting passage that I could slow down & enjoy a bit. That happened from time to time, but nowhere near often enough.
Kind of a bummer, too, because I enjoyed some of the prior installments. Three stars is maybe a bit generous, but I don't want to crap on this any more than this review already has.