I agree with the OP. Season 1 was a thrill to watch. Personally seasons 2 and 3 get progressively worse, I'd call them boring and rudderless. Season 4, the final season has a lot of payoffs but I honestly don't know if it's worth it getting to that point slogging through the rest of the story.

That being said all the characters feel very human. They're not simply plot elements, even the side characters. Everyone reacts according to their own beliefs and characteristics. There are consequences, intrigue and hidden agendas behind every action. At times the intrigue goes a little too deep as you can tell the writers got a little over their heads at times.

It's really hard to say much about the series as it's kind of chock full of spoilers, though. Even making comparisons to other media feels a bit too leading. You really need to go into this show with blinders on. Just watching the first 15 minutes should give you a good feel for the vibe of the rest of the season though.