I finished season two of Reacher. I liked it, but I have a few quibbles about it. I am not a fan of the tendency of TV writers to decide to rewrite source material unnecessarily. In this case they decided to add the angry detective sub narrative. It's reasonably well done but a cliché.
Also, at the end of the book there is a touching scene (pun notintended, but recognized) where Neagley briefly reaches out and touches Reacher. It is well established by that time (Bad Luck and Trouble is book 11 in the Reacher series, more on that later) that Neagley does not like physical contact with other people, presumedly because of some trauma in her past. Her pushing past that to touch and hold that touch with Reacher is a tremendously poignant moment in the book that speaks to her own issues and her affection for Reacher. Moving that moment to the TV writer created detective was an OK TV moment (though it felt a little contrived to me) but it lacked the power of that moment in the novel and misses the way that touch helps define in expand upon the relationship between Reacher and Neagley, particularly coming after the Karla Dixon affair.
I felt that using Bad Luck and Trouble as the second season of the TV show was a mistake. As noted above, it is the 11th book in the series. By that time, Reacher is a well established character and adding his former 110th team expands what we know about him. in the TV version, it almost seem to take away his uniqueness. Instead there was a whole bunch of mini Reachers.
Also, the storyline that the 110th Special Investigations Unit existed briefly and was disbanded is different than the novels universe. Remember the movie Never go Back? Well, reacher is going back to the 110th. One of the funny subplots in the Reacher series Is the question of how he lost command of the 110th. We know that the answer involves a dent in his desk. In the book Never go Back we find out that the dent was created by Reacher slamming his CO's head against it. Waiting for that scene at the end of season two, but instead we got the "Party scene."
I could go through more stuff but this post is already way too long. I will say that the violence in the novels, and there's an awful lot of it, never seems contrived, mean spirited, or sadistic. It's always either necessary to advance a goal or justified pursuant to Reachers moral code. in the TV series it just seems to exist for its own sake. They did a better job with that in season one.
All that said, I enjoyed season two, but as a fan of the novel series, I wish the writers would stay closer to the source material.