I didn't fully get Ikkitousen, but I found it fairly enjoyable anyway. The premise is that there are these highschool students who have earings called "magatama" which represent, as far as I can understand, the souls of great warriors from the past. Along with these earings, the students inherit not only the warrior's fighting powers, but also their destinies. Each highschool sends out its students to battle each other in a re-enactment of the Three Kingdoms era.
Fanservice: The anime is an ecchi. Specifically, that means if you see a female character in a given episode, each one of her two tits will be larger than you can cup with both hands; and before the episode ends you will eventually see the majority of the surface area consisting of her breast (though you will never see a nipple), and her panties (and you will never see genitals, though you may see buttocks). Every now and then, you'll see one character (sometimes male, sometimes female) gropping another character's (always female) breasts. I believe fingering happens twice over the thirteen episodes, though it will always be at an angle where one could claim at best PG-13, at worst PG-16 (like the blowjob scenes in American Pie 2).
Characters: There's something like five female characters, and they each have different colour hair, so it's easy to tell them apart. The lead character is one such female, called Hafuku Sonsaku and the warrior infused in her is Sun Ce (though they never actually come out and say that in the anime; I had to look it up on Wikipedia). I can't really remember the names of any of the other characters, male or female, except for "Mou-chan". As for the male characters, there's also five of them that are "important", and then dozens of other serve as "stormtroopers" who get their asses kicked by the more important characters. I can't remember any of the male character's names. Sometimes I can't tell certain male characters apart though, because they simply look too similar. It's a "fighting" anime, like DragonBall Z, so the episodes don't really dig deep into each character's personalities much. After it's all over, you'd recognize the characters if I showed you pictures of them, but you probably won't emphasize with them much at all.
Plot: It's original, to me at least. The underlying theme seems to be fighting one's destiny. For example, one character has the Magatama that says he's the leader of this particular kingdom, but eventually this other person's going to come along and assassinate him. The character who has the magatama of the assassin is going to try to fufill that destiny by hunting down this particular student. Will the leader be able to escape his destiny, or will he succumb to it? Well, that's the whole cliffhanger of the anime. The series is 13 episodes long. During the first 8 episodes, it's just straight forward fighting. That's fine. It lets the series introduces all the characters of the story, and establishes a hierarchy of who's who. By the eighth episode though, you start to wonder how long the fighting is going to continue, and when the actual plot will kick it. Luckily, it does right at episode nine. A big plot twists happens, and that's then it resolves itself by episode thirteen. And that's the end of the series. Which again, isn't bad. But it does leave a "That's it?" sensation once you've finished the thirteenth episode. The ending is the part I didn't fully get, by the way, as it seems it assumes the viewer is at least passingly familiar with the actual story of the Three Kingdoms (and I'm not).
All in all, this anime wasn't anything spectacular, but I certainly don't regret the time I spent watching it (unlike say, Evangelion, GTO or Last Exile). I had the feeling that I missed some of the sublte references to Chinese history, but big deal. It was still fun, mindless entertainment. 6.5 out of 10.