The premise of Yugioh is that a young High School boy solves an ancient Egyptian puzzle that unleashes another self within his mind. This other self challenges those who do evil to karmic games and destroys their minds when they cheat. The story is laughably bad. The games are different in virtually every episode so they constantly have to take time out of the action to explain the rules for the episode. Add that to the fact that the other Yugi frequently wins through pure BS, I mean the power of friendship, and you get a story that's so stupid and cheesy it feels like an old B-movie. To Yugioh's credit there are some really funny moments, although most of them are unintentionally hilarious as a result of how bad the anime is.
The characters are what really hut the anime. Most of the main cast is composed of complete twits. There's ordinary Yugi who acts like a small child. Jonouchi Katsuya, who's your typical thug with a decent heart. Honda, who is very bland and never shuts up about being a beautification department member and Miho, who is useless. The only characters who are somewhat interesting are Yugi's other self, Bakura and Anzu. Since they actually get some depth. The antagonists are all pretty typical as well.
The art is atrocious. Everything's done in bright neon colours that can get painful to look at sometimes. There are also a lot of art errors. This makes Hitsuji no Uta look really professional.
The voice work is actually pretty well done. Ogata Megumi, Shiozawa Kaneto and Midorikawa Hikaru are especially good. The music is also very good so sound is one thing they did right.
The yuri factor is a 2/10. Miho shows some homoeroticism towards Anzu, but Miho also spends a lot of time chasing guys and Anzu doesn't show a lot of interest in her so those moments don't amount to anything.
My final rating for Yugioh is a 3.5/10. It's bad, but it's bad in a way that's pretty entertaining. It's sort of like Adam West's Batman. It's bad, but it's also fun to watch. So, even though it is bad, I actually do suggest watching it, if you enjoy media that's bad in an entertaining way. In fact you should get some friends together and snark it. Just don't marathon it because the art really is so bad that it's hard on the eyes.