Story: To summarize the plot with no spoilers, it's about a boy named Ganta who is framed for brutally killing his entire class and sent to the prison "Deadman Wonderland." While he is there, he is seeking out the person who actually killed his friends. The holes in this story were so numerous I would have mistaken it for a construction site. The practices within the prison are so inhuman there is no possible way to have kept it all a secret from the government who would shut them down (they were selling tickets to the public.) Not to mention, the prisoners are somehow able to stage massive attacks on each other and everyone seems to just look the other way while they bring down large sections of this, claimed, high security prison. The list of flaws in this show is endless, however I still enjoyed it. The plot was so unbelievable I eventually just accepted it as and enjoyed the very bizarre world that was set up before me. I was disappointed at the ending though. I could tell it was being set up for another season. Yet, whether they will get it or not depends partially on the demand of the fans. As far as I hear, a second season isn't looking all together promissing.
Animation: It was very wild and very well done. I liked the fighting scenes and I thought the character designs were all interesing and unique.
Sound: I liked the voice actors a lot. I thought they suited their parts perfectly. The music was not particularly catchy, however. I didn't think the background music stood out at all and the closing theme was so perky and happy I had to wonder if they actually knew which anime they chose it for. The opening, on the other hand, was gritty and gets stuck in your head. I didn't realize I liked it until I heard myself singing "So make me your deadman!" while I was cooking dinner.
Characters: The characters are a hit or miss. I loved them. I thought a majority of the characters were incredibly epic and very strange. However, that is not to say most people will like them. I enjoyed the fact that every single character in it was, in some way, evil. Almost everyone was either an open or secret psychopath. That being said, if you want a show with likable characters who you can empathize with... this is NOT your anime. If you want to see a lot of very epic and very crazy people fight to the death (or until they have lost a couple of limbs) I think you might enjoy it.
In other words, it's not flawless. However, it is epic, intriguing, brutal and full of action. It has some great twists in the plot and I was never bored.