I only watched it recently for the first time. I like the main actress (what a name, Morfydd), Arondir and Durin, while the Harfoot parts in general I found rather boring. I don't have any complaints on casting. the only real issue of the show is that it simply isn't as good as it's supposed to be, but you don't really think about that during the first watch. right after I finished it, I rewatched LOTR trilogy for the first time in about 10 years I think. only when you compare the show with original trilogy you realize how good such show could actually be and yet, this doesn't even come close to offering similar experience. I mean, I like it and would rate it with 6.5 or 7, but I bet simply liking it isn't enough for people behind the show given the effort and money spent on it. it simply doesn't hit like it should.
and yeah, that scene in prison was brutal. stormtroopers look like able warriors compared to those guards.