Akagi is a delight, and I feel that is in large part because I read it after it concluded.
Akagi's glacial pace not only does bother some, but would have driven me up the wall, as well, were I following it while it was being syndicated. There's an entire volume dedicated just to them DRAWING THEIR STARTING HANDS. As in, not a single round is played! Not even Saki, gradual as it is, can drag a single match on the way Fukumoto does it! He is an absolute madman.
Speaking of Fukumoto, one of his defining traits is his unusual art style that I'd hesitate to call pleasing in any sense. While it's not nice to look at, I don't think there is a need -- in fact, Fukumoto's ugly art plays to Akagi's advantage by guiding you through the panels with such speed that the otherwise spellbindingly slow pace of the story hardly registers. You don't have time to sit and focus on a beautiful panel or delectably-drawn figures, you don't need to, there aren't any, you can just read and read and advance and progress until you reach the conclusion!
The conclusion which, with no spoilers, I found quite satisfying. When you build up a single game for twenty years, it's hard to think of a scenario, win or lose, that would satisfy a loyal audience sticking with it. I think what Fukumoto pulls is perfect, both story-wise and for the readers who hung in there for the ride.
You probably don't need to know mahjong to enjoy Akagi, but I think a familiarity with it adds a lot to its appeal. Seeing Akagi's different methods of faking out opponents, understanding why and how the characters fold or call in order to upset the draw order, and following along with the lines of thought that you're constantly riding with (Akagi largely takes place in the characters' minds moreso than on the board) all add to the inherent thrill of a life-or-death gambling match. It's rare that a manga has me on the edge of my seat, let alone in a board game match, let alone let alone a single game in a single night.
Akagi is great. Is it long? Very. Must it have been torturous to read during serialization? Undoubtedly -- I'm surprised Fukumoto never got strangled for this twenty-year long night. And I'm glad he didn't, as Akagi is fun as hell if you read it in one go.
Also, as a side note: Akagi Shigeru himself has big millennial energy, what with his desire to bleed a millionaire of his money dry at the potential cost of his own life. He doesn't fear death, he just wants to take down the rich man in the most humiliating way possible, and I think many of us can admire that. It certainly endeared him to me.