...pretty good I think! Watched it on Crunchyroll today (woo 720p), and found it to be pretty exciting. You don't need to know much about mahjong (I don't) -- it seems to be a lot like any sort of, "let's enter into a competition, yea!" sort of anime, like Angelic Layer.
Again, props to Crunchyroll to licensing it for distribution. It was pretty smooth too, now that I've figured out how to get hardware acceleration to work consistently (right-click the video player while in normal mode, enable HW full screen accel, then make it full screen). The video stutters occasionally, but it may be my computer not having enough processing power.