So, disclaimer, I only made it halfway through the first episode before quitting in disgust...
1) Completely missed 'the point' of the book series, by trying to make it a story about humans rather than a story about humanity as a whole even with the characters it does focus on.
2) Messed around with the timeline, introducing key points of the story before they made sense (the countdown and the blinking stars for example).
3) Broke some characters into multiples for no reason (other than to apparently fill some kind of 'diversity checklist'), robbing some characters of their agency and story arcs. I can't even understand why these people would be friends let alone imagine how they would represent differing aspects of the original character. There's none of that 'friend' chemistry there (in fact it honestly feels like they hate each other for the most part). Shi Qiang should be a character you start to hate but grow to love for example, representing what humanity needs to sacrifice if it ever wants to survive. I couldn't hate Benedict Wong if he pissed in my morning coffee
4) Where the Tencent series often felt plodding and slow (and could probably have been at least two-thirds of the length it was), the Netflix version feels rushed, almost like the creators couldn't wait to deliver the final product and run out the door before Netflix could ask for their money back. 30 minutes into the first episode they've already hit plot points that don't appear until halfway through the first book and about 8 hours into the Tencent series, which make me wonder where the hell they're going with the rest of the episodes.
These four points were worth a review star each - the remaining one is that they at least gave it a try and might get some people to actually ready the book or give the Tencent show a viewing (and then realise how bad a job was made of this).
People gave Benioff and Weiss a lot of latitude with the last season of GoT because 'they didn't have source material to work from' - here they had the full source but STILL managed to screw it up
[EDIT] I actually went back and watched through all the episodes as no doubt somebody would accuse me of 'not giving it a chance' and it gives me no pleasure at all to say that it actually got worse. The moral of this story is 'always go with your first impressions'...