How was Crucible? I haven't read any TOS by DRGIII yet.
I thought the McCoy book in the trilogy was just flat out awesome. One of my favorite Trek books of all time. The Spock book is very good. The Kirk book didn't speak to me as much but still very solid.
It just doesn't bother me at all the trilogy is stand alone. In fact I think that helps it. Since it doesn't tie in with any of the other books there are some actual surprises. And TOS has never had a long history of having the novels tie into each other anyway.