Ive read Liar Game, bits of Kaiji/Akagi/Gamble Fish, and a few other psychological or game based things. Personally, Gambling Emperor Legend Zero is the best of them in my opinion. Ill go through each of story, art, character, and then tell my thoughts in the enjoyment and overall sections. There may be spoilers for some of the games.

Story

A group of people are gathered to play games of intelligence, risking their lives to get three rings, which will advance them to the next stage. If they fully win, they will be able to earn a fortune, and numerous people aim for this. Zero joins as well, but the games are not simple. A simple "medium" level game would require risking your fingers (and nearly getting them cut off), while other mediums or hards would require betting your life.

While I dont think the premise is the greatest, the setup works in my opinion for these games, and I really enjoy the various games and clever solutions. Many of them are unorthodox, but I find those even more enjoyable. The pacing is much better than manga like Kaiji too, as it moves along well and isnt purely psychological; it has a nice balance of Zero's internal struggles and the external issues at hand. The high risk compared to manga like Liar Game increases the tension for me, and I prefer this one as a result. The main character also still fails, despite his geniusness, which I quite enjoy.

Art

Typical of the author. In my opinnion, the characters and design are very ugly. I dont particularly care though, since I like the trials of intelligence and wit so much more. The action and backgrounds are understandable, and I can tell whats what, so thats enough. I also do like how some people look, like Zero and Shirube at least.

Characters

Many have compared Zero to a Robin Hood of sorts, and I would agree he is to an extent. I enjoy watching him constantly save people and try to prevent any deaths. This is augmented by how the series started with a suicide pact, which Zero saved the people of. It was a nice loop, to the beginning.

Zero is very smart, but you can see his humanness, as he does make mistakes such as being overly trusting, and you can also see him sometimes lose out to others. Theres one side character in the mafia who is also very smart and almost beats Zero to the punch in one of the trials. Shirube in particular is a completely superior rival, as Zero never managaes to overcome him at all. I find Suezaki and most other characters pretty bland, but once again, I find the characters tolerable enough given the enjoyability of the gambles.

Enjoyment

Okay, so based on what Ive said, I think you should have an idea of if this is gonna maybe be enjoyable for you. I really only recommend this for those who like gambles and games like I do. The high risk gambles are tense and exciting, and its the best and main reason to read this manga, even if you have to suspend your disbelief.

Overall, Id say this is highly worthwhile if you liked things like the mind games in Liar Game, but if youre looking for more characterization or real storylines, you may want to look elsewhere.

P.S. I do NOT recommend the sequel, as it is completely different and imo extremely bad. This first series is very enjoyable and ends on a weird, unresolved cliffhanger, but I personally was indeed satisfied with Zero's accomplishments.