In Juuni Taisen, 12 warriors are battling to death. That's it, ok. So, the first impression of the anime was: "There are going to exist a variety of strategies for each warrior, and this is the anime focus." But no. The anime focus on the past of each warrior, to see their difficult past.
Let's start by the Art and the Sound (7 and 6, respectively): The 3D element is well used in the anime, and that was the only thing that caught my attention about the art. About the sound, well... I like the opening.
Character (8): The characters are very well made, and have defined types of thought. As the anime shows their past, the characters gets closer to the viewer. The exception to the rule is like, the Horse.
Story (5): It have no story, its literally 12 guys fighting to grant a wish. Just that and the backstory of each warrior.
Enjoyment (4): Sounds like a cliche right? But it isn't. It presents a Fate type of story but it tells us the backstory of each character, all in 12 episodes. I didn't watch the entire anime, at this time I've completed 10 episodes, but it is very boring to watch because is predictable.
Overall (6): Watch Juuni Taisen if you like to see individual stories, because the main one it's just so irrelevant and predictable that it turns out to be boring.