When Titan started I loved it. Exploration in Star Trek, what a concept! The first two books were tying up loose ends from a number of sources but then it was full on Strange New Worlds. Boo-yah!
Then somebody decided that Michael Martin should write Titan and things went downhill fast. Titan went from must read to wtf? to sorry, no. Until somebody who can actually write a compelling exploration story takes over the series Titan is off my list.
Mangels and Martin co-wrote the first two books in the series, but of the subsequent novels only the most recent was written by Martin. Mack, Bennett, Swallow and Thorne have written the others.