The following review has spoilers on both the manga and both seasons of the JDrama:

As expected, there is the same cringe-awful acting. However, not without high production quality, great set designs, and even clearly articulated game rules.
In Season 1 they actually expanded on the source material and gave the bone some more meat.
In Season 2 they fucked up with the two best games in the entire series 💀💀

King of Clubs
Niragi becomes even more one-dimensional than he is in the manga. Instead of being the MVP of the game, his original 1st phase plan is changed to Arisu's plan instead. Despite his demeanor, his specialty is actually diamonds (intelligence). Here, he's just some dumbass rapist overstaying his welcome. The whole reason why he and Chishiya battled in the beach game is because they're meant to be parallels to each other, but here it's like comparing Einstein to Andrew Tate. Even his conflict against Arisu & assault on Usagi is dumbed down with little to no impact.
Kuina on other hand got it even worse, her opponent clowned on her completely. This is meant to be her peak in the entire series and she gets jack shit. Instead of being beat the fuck up, she gets a simple tackle. Instead of doing a hardcore counter kick where both her and her opponent take each other out for a distraction - she just easily gets swatted away. She is even presented as the one who failed to end the game early and thus eventually leading to Usagi's scuffle and Tatta having to sacrifice himself instead. Heck, instead of being the one to declare that she'll do anything she can to get the final 2500 point item, that speech is passed onto Usagi instead. She doesn't help at all and just waits pathetically for death. Character over lmfao. Epic trans rep Netflix!
Additionally, Arisu's final thank you speech falls flat and he doesn't even make up with Usagi in this game (he just hangs her up to dry until things boil over). Furthermore, the final 10 minutes were literally animanga logic timing, entire important events happening in the span of a single minute. You as a viewer can see the timer at the bottom and these characters have entire 5 minute dialogues and apparently only 2 minutes have passed.

Jack of Hearts
They condensed so fucking much lmfao. Half the characters are just disposable nobodies. Buildup & insight for Banda and Yaba are non-existent. Chishiya is for some reason incorporated into this game when he isn't in here in the manga (which tbh is welcomed as his actor is amazing). But it still feels like he's hamfisted in there because he's a fan favorite. The tough guy at the beginning is a 0-dimensional meathead and his victim doesn't get any agency in the slightest, the intimidation & conflict was even worse than your stereotypical animanga comically evil class of school kids. All the well-crafted backstabbing is dumbed down. Even the Jack himself gets character assassinated with little to no substance. But by far the most egregious is the "equality" speech from Yaba being cut almost entirely, thus falling flat on its face and ruining the keikakudoori moment.

Episode 7 Compilation of off-screened games:
- King of Hearts - ppl are for some reason running around in a tight maze away from unknown creature (lame as shit for a hearts game wtf)
- Queen of Clubs - orb throwing game on a tight platform (how is this any shape or form a team game, 90% of it is physical fitness AGAINST other groups of people.
- Jack of Clubs - a bunch of people climbing numerous amounts of rope (once again, what the fuck does this have to do with teamwork, 90% of this is physical and it even shows us ppl kicking each other off)
- Jack of Diamonds - unremarkable Mahjong game with Chishiya OMITTED
- Jack of Spades - martial arts battle royale with Kuina iirc...yeah that's it
- Queen of Spades - 2 team tag game in a massive parkour arena, barebones writing and minimal substance aside from set design. Only exists to give Arisu & Usagi another game together.
- Queen of Diamonds - Unclear; only the aftermath is shown where a huge number of injured people are seen running out of a car park.

Remaining 4 episodes of season 2:
- Camera guy motivation cheapened and insight into dealers erased
- Doudou does not exist - good choice.
- Heiya's incredible backstory is a lot less substantial, visceral, and cathartic.
For some reason ended up powering through half a magazine close-range m16 rounds for several hours while crawling across cement and rubble instead...ok.
- Chishiya is not present in Jack of Diamonds
- Yuji Mahiru's story is assimilated entirely into Ann but any of that profoundness and nuance is lost to some random ass pretentious landscape shots of some mountains. Actual nothingburger of a character, both in manga and adaptation.
- King of Diamonds: They made the loan shark woman a complete dumbass for some reason, why did they characterize her like it's her first game or something. Aside from her college-level math skills - why in the fuck would this person join the king of intelligence game? And her fun little segment with Chishiya where they help each other is completely removed as well. We just completely off-screen how Chishiya won 2 rounds because they made her a dumbass. Also lmao, Chishiya omitted the 69 comment.
- Kuzuryu's character is also a lot less nuanced with both his and Chishiya's motivations, backstories, and character introspection made ambiguous and up to your interpretation.
This wasn't the producers expecting their fans to have reading comprehension skills in order to come to their own conclusions, this was them making it broad and muted so that it would sound philosophical & deep and the fans would just simply nod their heads to it.
- King of Spades - Wow, while they only slightly alluded to his "mercy kill/ending agony" motivation unlike in the manga where it's made blatantly clear, I actually like how he was handled here. Amazing fight choreography and an actual great culmination of character drama & climax. Mf actually soloed the entire cast and was killed off climatically by Arisu & Aguni. Good shit.
- Queen of Hearts - fucking near-perfect, so masterfully done. Actually got goosebumps even though I knew everything that was coming.

- Ending - R.I.P LMFAOOOOOO FINAL CHAPTER'S MESSAGING COMPLETELY OMITTED, THE BEST PART OF THE MANGA ERASED AND FELL TO NETFLIX CURSE ARE YOU KIDDING ME???
FUCKING "JOKER" CARD SEQUEL BAIT INSTEAD????????????????????????????????????????????????????????????