Yu-Gi-Oh! Online is basically the best thing that Konami has done with Kazuki Takahashi's dangerously popular, tween-focused franchise since it started cranking out lo-fi Yu-Gi-Oh! games some six years ago. The ability to play the Yu-Gi-Oh! card game against other Yu-Gi-Oh! enthusiasts over the Internet is the only thing that separates this game from the seemingly hundreds of thousands of Yu-Gi-Oh! card-battling games released before. For established Yu-Gi-Oh! fans, whom this game was tailored almost exclusively for, it will be enough.
Yu-Gi-Oh! Online is...well, Yu-Gi-Oh!, with online play.
Yu-Gi-Oh! Online is not a terribly inclusive game. It makes a lot of assumptions about your familiarity with not just the overall card-battling philosophy, but also with the mechanical minutiae of the Yu-Gi-Oh! card game, and the smattering of in-game assistance is largely limited to helping you navigate the interface. There is some online explanation of how the game is played, but this quasitutorial comes off as dense and convoluted. If you don't know how to play Yu-Gi-Oh!, but you at least have experience with another collectible card game, you can reasonably assume that you'll pick up the specifics as you go. However, if you have no collectible card game experience whatsoever, you're better off picking up one of the older, offline Yu-Gi-Oh! card games on the cheap, as the competition is downright merciless online, and the suspicious pricing model doesn't really encourage trial by fire.
But if you already know what's up, Yu-Gi-Oh! Online makes it easy for you to quickly jump into a game. When you first create your account, you're given a random deck of 40 cards and then you're dumped into a lobby, where you can either directly challenge another player, or just let the game match you up with another player. You will be matched up with other players of the same level, but since those level designations are inexplicably reset at the beginning of each month, it stands to reason that you're most likely going to face a more evenly matched player at the end of the month than at the beginning.
The game doesn't really bother with too many interface flourishes, and as such, it ends up looking kind of lean, with more of a focus on functionality. The usual faux-Egyptian flavor that Yu-Gi-Oh! has been peddling for nearly a decade now is present and accounted for, and the melodramatic orchestral music that's peppered with some vaguely Middle Eastern instrumentation generally complements the look, though the music does get repetitive quickly. Even by the relatively modest standards of other card-battling games, the visuals in Yu-Gi-Oh! Online come off as stripped down.