The first two Crucible books were great.
But, it felt like the author was building toward some deep revelation about Kirk's character in the third novel. What was really going on inside his head as he stepped off the transporter platform after Edith's death? How did her death affect him so deeply, and why?
However, as DRG3 said in the intro to book 3: "I can't write that book" or something to that effect. Instead, it was a very surface level adventure story, very short, very little character insight. (Character insight is what had made the first two great.) On the whole, the trilogy is worth reading, at least for the first two entires.
But I felt like the third book punted on the whole premise of the series.