It's trying too hard to seem smarter than it is. And that spoils the spoils the show along with its length, since it probably should have been a 2 hour movie.
Personally, I knew who the killer was right away, but my reason was "it's the only person I recognize, and their playing capacity allows them to play a killer". But as is it's not like it was too obvious. There were hints, of course, but there was enough ambiguity to keep up the mystery, even though overall presentation was kind of "meh". The first 5 episodes felt long with some unnecessary long shots and scenes from different times. It's surprising that the time was not spent to show more of the characters' past and to feed us more suspicions ,maybe that's a blessing in disguise.
When the 5th episode ended, I was thinking, that they went for an open ending, but... No, I had to sit through the last episode, and that ruined everything for me. A big part of that is abundance of cliches from old US "heroic" movies. I won't spoil anything, but you will understand what I mean, when you see them: things that we accepted in the past (and sometimes still do), when movies were not trying to be realistic, but they stick like sore thumbs in this show, that is trying to be somewhat realistic.
I could laugh those off, but not the plot of this episode, which made even less sense. There was a twist, that I did not anticipate (and which made the other twist more predictable), but I did not, because it was stupid. The show was trying to look like there was a complex operation, which went off script, but still was almost per plan. Not literally, but as if the character was so extremely smart that was able to pull things off, but all of it was pure luck and nothing else, and if one was smart, indeed, they would not do such things.
If the show ended at episode 5 - I would have given it 6/10. If the last episode was kind of a "recap" of previous ones from perspective of the killer with ending showing how they "escape justice" all that smart and "cool" - depending on presentation I might have even given it a 7/10. But the stupidity of the actual episode makes it 4/10 for me, maybe 4.5/10.
