The books didn’t feel the same without Mangels.
Yeah, this is totally opinion, but the way that things played out in the Martin-only books, it left me with the impression that he was a world-builder first, and Mangels had been the character-focused writer, and it left me metaphorically thinking that the writing duties went to the wrong "parent" in that "divorce." Kinda similar to my issues with DRG's handling of post-Destiny DS9, come to think of it, where he focused so much on the big picture, of making sure that all the pieces on the board were where he wanted them to be for the payoff that he seemed to lose sight of the motivations of those pieces.
As for the Romulan War books, I very much get the impression that the first book was written with the expectation, or at least hope, that there'd be a third book, because the second book does feel a bit more rushed than the first, with various elements seeming like they were something that were meant to have more focus and attention or development, but compacted down into the shorter page count of one book instead of two, especially when you start getting in to the time jumps, which pick up relatively as the second book goes on in comparison to the first.
Even with me not being as enamored of the solo Martin writing, I would have liked to have gotten that hypothetical third book, if only to give the story beats a little more time to grow naturally. I think that, despite actually DOING something with Travis, he still got shafted in that compression down to two instead of three books, not really feeling like his arc really got to portray him going from anger at Archer over the events of Kobayashi Maru to finding peace over his decisions. Though, still, points for even making an ATTEMPT, considering how the show failed to even make that much effort with him.
