This is a review for the second book in the Koban series by Stephen W. Bennett.
Apart from a few incongruities I liked the first book of this series ("Koban") a lot and was looking forward to the sequel. Unfortunately "The Mark of Koban" fell short of my expectations. Instead of improving upon the few things that didn't feel quite right in the first book, the sequel feels a lot less thought-through.
The story can easily be summarized as follows (mild spoiler alert for this paragraph): the Krall are attacking humanity, and humanity responds by reintroducing ground armies, but they don't do very well. The Koban humans improve themselves by genetic engineering to such an extent that they really aren't in danger from anything. The can single handedly beat Krall warriors, have rippers as pets, and telepathy (at first just on contact, but later they discover that it also works over astronomic distances through tachyon space). In the end they capture three Krall ships and go after the Krall's supply lines. This is where the book ends.
As you may have already concluded from the above summary, the book is really way too long for the stuff that actually happens. One reason for this is the lengthy description of the Krall raids on different human planets. Unfortunately, both the planets and the characters attacking and defending them are only introduced for this sole purpose. There doesn't seem to be any connection to the main story line, and as a result I quickly stopped caring about both characters and outcomes. If the goal was to give some indication of the Krall's progress, this could have easily been achieved by cutting all the planetary assault scenes to just a few pages.
Another problem with the book is that many scenes seem completely artifical. There are several parts where characters begin a conversation by "reviewing" the events of the last x years. In another scene two couples simultenously discover that they can read each others minds when they both touch a ripper's frill, and the first thing they say to each other is that they accept the marriage proposal and they're willing to do some nasty act they were thinking of. And that's it. After that, telepathy is pretty much an established thing for the rest of the book. In a third scene the geneticist giving someone an injection starts by "reviewing" the terminology that they have established for people with different levels of genetic enhancements: SGs, SG1s, TGs, TG1s, and some. That terminology is then actually used throughout the rest of the book by people in conversations ("My son is a TG, but he wants to become a TG1"). To me this seemed as if the author was just using some placeholders with the intention of later revisiting this.
So, to summarize: very little is actually happening in Mark of Koban, and the book fails to build up any tension (either because the reader doesn't care about the characters, or because the characters just don't have anything to fear). Many scenes are implausible and pull you out of the story. Overall, my impression is that this book was published too early. It could have been a lot better if the author spend some more time on it (as he demonstrated with the prequel).
Verdict: skip it.