Not OP but I'll give you a break down of my thoughts on what makes it good:

1. Narrative format. Elliot "breaks the fourth wall" by speaking to the audience in voice overs, which results in some interesting dynamics and plays an important part in both the plot and his character development. It's probably one of the most effective uses in voice over narrative in TV since Wonder Years.

2. Direction. The direction of the show is just unique and also very effective. The camera shots, framing, angles, are all used to help influence our views, feelings towards characters, and understanding of what's happening. After season 1 there are some very well done scenes that make use of long shots and revealing of scenes as things unfold on and off camera.

3. Characters. Like Sopranos, these characters are treated very much like real people. They get into crazy situations and it effects them. We see how it effects them over time. They change, their relationships and dynamics to one another change, and all of this effects their choices and the larger plot. It's a psychological show, with a psychologist as an occasional character (like Sopranos), so it takes into consideration how the psyches of people work. And there are some fascinating characters, some who aren't even main characters, and they all have complicated depth.

4. Plot and story. Mr. Robot is a show that moves forward while still returning to past effects. The plot develops with each season, though season 2 is a little more character focused, and it kind of just keeps unfolding. But, essentially, the plot and story is all really about Elliot and Mr. Robot, which is why 1, 2, and 3 of my list here are handled so carefully. It needs those elements to work well for its story to be good. And so there's an attention to all of it that helps it become a well crafted story.

Overall, it's good TV because it's aware of its medium and craft and how to use those effectively. This also makes it a bit too "pretentious" for some, because it very much is trying to make an art out of it, it's aware of what it's doing. That's not for everyone. But I think if you enjoy character driven stories it's still good even if it feels a little too meta or pretentious at times.

It does use similar fantasy scenarios as Sopranos, where it delves into the mind of the protagonist like we do with Tony, but it really pushes on that farther and takes it up several notches. That can be too much for people when it happens, but it's not every episode either.

Anyway, that's what I think makes it good. It's firing on all cylinders and fits the genres I like. But your own tastes may differ.

It pulls you in harder than just about any show I've watched. It keeps you on the edge of your seat for almost the entire series, kind of like breaking bad but much more engaging and fast paced. And it doesn't even have a massive buildup, it hooks you from the first scene and will keep you guessing the whole time.

Control is just an illusion!

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.