You're entirely correct. I devoured the books years ago, and then almost immediately bounced off the show because of the changes. Thankfully I pushed through it, but the show is very much doing it's own thing.

Fair enough, I personally see the changes as a benefit as the source material is pretty dated although still incredible for sci-fi written in the 50s.

I might even go as far as to say it's the best book-to-film adaptation I've seen for that very reason, as you say it kept the high points of the books and it's aim was clearly not to faithfully recreate them for reasons that become somewhat obvious at the end of Season 3.

Definitely agree on Pace, Birn and Mann, rarely do you see such good acting in a sci-fi series.