This game was memed so much that going in, I had surprisingly little knowledge of what actual experience I should expect, so here are some of my spoiler-free notes. These by no means cover everything relevant to know about the game in advance, just some things that jumped out at me.
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This game borrows heavily from the immersive sim tradition. A lot of "quirks" will seem immediately familiar to anyone who's played Bioshock or any of the Deus Ex games; most prominently the hacking system, the "caper" framing of most tasks and the multiple possible approaches to each of these "capers".
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I won't blame anyone for calling the exposition and the setting "cringey", "cheesy" or "over-the-top" but to its credit, the more the game progresses the more the setting matures and comes into its own. By the end I was eager to engage with the setting on a more meaningful scale, even more eager than the game ultimately allowed for.
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Choices kind of matter occasionally and for the short-term only. This isn't Tyranny or Mass Effect. You can set the flavor of what the main character says, but the course of the plot is mostly set in stone. Exceptions to this are sidequests, where a wide array of outcomes is possible; and endings, of which there are about 4 or 5 that you can unlock depending on whether and how you resolved some sidequests. The game won't mollycoddle you about your ending choice, be ready to live with the consequences of your actions.
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At some point 1/3 of the way into the game the deuteragonist Johnny is introduced (this is Keanu Reeves' character). The thing is, by that time you've spent exactly enough time immersed in the game's various factions, conspiracies, pushes and pulls to care about them much more than this Johnny, who at first comes off as a distraction, an obstacle. But having played the game, in retrospect I can say most of the narrative effort of the main plot is spent on Reeves' character. The rest of the main character's problems, friends, enemies, hopes and dreams just kind of come and go and pass him by, sometimes very abruptly. When you see Reeves' character just buckle up and accept him as the main act from that point on, for better or worse. If your immediate thought is "I can't stand this asshole" then by all means, spend the game stewing in that thought.
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Yes, this game has the infamous "AT HIM! Where's your pretty stealth build now huh" third act conga line.
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There's a point in the game where you say to yourself "hey, I'm a badass now, I can handle myself". But before that point there is a phase of early game hell where you had better mind your own business and stick to the main plot and to quests where the danger is "moderate". I played on hard difficulty and in the early game, getting involved in any ongoing incident or high-level sidequest was a death sentence, no matter what clever strategy I tried. YMMV obviously.
At this point if you haven't played yet I might wait for the DLC to come out--it's apparently making fairly substantial changes to the entire game's (including base game's) systems and gameplay. It won't change everything the OP highlighted, but will supposedly address a lot of the gameplay, stat/cybernetic management, and further AI changes or fixes. I played earlier this year and despite some persisting flaws would still recommend it, but if half of what is alleged about the DLC changes are true (and that's still an if until it actually releases) the game will be in an even better place then.
Do you know whether or not the gameplay and system updates will be free, or will it require purchasing the DLC?
Word on the street is that the updates will be free. They also announced a two-part update, with the fixes coming first followed by the DLC.