1) Some players expected this to be cyberpunk-themed RDR2/GTA5. It turns out it's nothing like that, it's more like a new Deus Ex game.
2) It just doesn't run on consoles. It's a very inferior experience, unless you're the type who can be happy with 2020 movies in .3gp format in your old Nokia phone. Having watched a video (https://www.youtube.com/watch?v=C5pHpQqhmR4) of how it runs on PS4, I now clearly see where all this hate comes from.
3) There are some bugs and quirks, depending on your platform and luck. I haven't had any major issues, though I know for some it's just unplayable at the moment. This will likely get much better after patches hit.
On a personal note, I like the game a lot. Yes it has its quirks, and I generally feel it's a less refined/polished game compared to what Witcher 3 was, but still it's an extremely fun, really well-made game. Combat is great, world is enticing, story-telling swings between good enough and great. For one reason or another whenever I launch the game another 5 hours passes without me noticing. FPS camera and general art direction also helps with suspension of disbelief, and the game is as immersive as it gets.
It's a shame that this game now has such a bad reputation for relatively minor & mostly avoidable reasons.