In contrast to most, I found the show quite boring. Considering many Netflix shows have horrible acting, this was a real waste of talent because these actors could act. That's the only reason I give it 2*, for the actors.
Disclaimer, I am a scientist so the science aspect wasn't mind-blowing or anything, it's stuff we've known for a pretty long time used in a somewhat believable context. However, because I am a scientist and it's sci-fi my bf thought I would enjoy it due to the many good reviews. I generally don't like watching TV and tend to leave it on as background noise while I do other things.
My bf and I binged it over a weekend, so we didn't find it confusing like what most people have claimed. Most people call this a slow burn, I call it extremely slow and frigid, if I had burns it was from falling asleep on ice. The problem isn't the premise of the show, it's that it requires one to completely disregard any form of common sense. To be fair, the show had a better script than almost all Netflix shows, they rarely said anything redundant or dumb, the camera and setting were all great, and within the realm of this made-up world, every puzzle seems to fit.
Unfortunately, the biggest issue is the suspension of disbelief that has become the theme for many TV shows nowadays, requiring the audience to lock their brains away in a safe. Do not question a single decision made by the characters or everything will fall apart.
If any of the characters figured out they could time travel and have been through the timeline at least once, why is the only plot a bunch of people killing or having sex with each other? Let's be honest, if I could time travel, I'd just settle down somewhere, buy myself a whole lot of stock options and invest in building my family fortune.
It was obvious from the beginning the main characters were the source of the problem, yet at no point did anyone think to pack a bag, leave Germany and head to say Australia to avoid the whole incestuous plotline. I mean... It's the sci-fi equivalent of mass produced horror films, whereby a bunch of stupid teens will always investigate the horror house. Some people may enjoy it, I found it completely idiotic. Frankly, I wouldn't mind a mundane film about people doing regular human things, it'd be more believable. Maybe I'm just more of a documentary-sort of person.
Edit: I just went through some other low ratings and it's funny someone else pointed out it's like a Telenovela, because I said that exact same thing to my bf about halfway into Season 1. It feels like a Spanish Telenovela with time-travel, and that's just not my cup of tea.