Not a bad Trek novel, but it really didn’t live up to the standards of the first two parts of the Crucible saga. It was a lot more confusing than the other two, and didn’t integrate nearly the background information on Kirk as the others had on McCoy and Spock. The writing was good, but parts did not make a lot of sense, and the story itself made a few changes to Trek Canon that the other books didn’t attempt to, and relied far too much on a single artifact from the original series.
Read McCoy’s entry, and if you like that one, read Spock’s. This one is NOT necessary to enjoy the others, and really isn’t doesn’t add anything to Jim Kirk.