First Manga I ever read, and now I'm starting to read manga, because Deadman Wonderland's anime was very incomplete, even though I loved the concept, and so I had the read the manga to get the answers I needed. And you should do the same.
So, a unique prison in Japan called Deadman Wonderland was built after an incident which involved an Earthquake. In this establishment, prisoners are in death row, getting slowly poisoned for 3 days and end up dying. However they can participate in circus like and entertaining events to an ignorant public from the outside world, thinking they are just "pretending" deaths. Igarashi Ganta, accused from mass murder of his classmates ends up there and meets Shiro and other characters that may help him on getting stronger, escape from the prison, claim his innocence, get revenge from the "Red Man" (the one who killed his classmates) and later with a group of characters, revealing to the public what is really going on. Some of the prisoners have special powers called "Branches of Sin". Those who have these powers are called Deadman.
The story is quite good, I really enjoyed the slow process trough chapters and explaining what could happen inside DW. When I ended up discovering more and more and unraveling more mysteries, the story gets even more interesting and I ended up reading a lot until I got to the final chapter. When a story sometimes "gets you" by surprise and ends up making your reaction being something like "Wooooooow!", then it probably is a good story.
I don't have deep arguments when it comes to manga art, since this is the first manga I have seriously read, but I quite like it, and in my opinion, it is well done, I easily understood what was going on in action scenes. I also loved the circus-like design from the prison, the bloody moments and the characters which are well made, speaking of which, Crow makes me remember of Bleach's Zaraki (xD).
Anyhow, about the characters, Shiro ends up to be more interesting than Ganta, in my opinion, because Ganta is that typical protagonist guy who wants to get stronger for a reason, and in reality, he is a weak guy. He ends up just getting very lucky for his "Branch of Sin" having something different, that's all, because he has no battle experience. It's somehow understandable that he tries to save and protect everyone (typical atitude of a protagonist too) and sometimes he ends up making decisions that brings bad consequences, but sometimes it gets a little tiring. Shiro ends up being more interesting because, despite of the sweet girl personality, quite early in the manga, you quickly understand she has "another mask", and finding out what's going on with her is just amazing. As the other characters, they are quite unique within the manga, and you end up learning about their pasts and the reason they ended up in jail and the way they somehow deal with their past thoughts. Gotta love each one's personality and traits. As I went further into the story, their importance gets even higher and I ended up loving them even more.
To sum it up, if you are one of those DW fans who got frustrated with the anime version, then read this manga, it is way better. If you are one those guys who love action, blood and also some mystery, read it too. The anime is asking for a 2nd season but since the answer is right here, at the manga chapters, I don't consider it necessary anymore. As you can see, most people made positive reviews about this manga, so it's probably worth it for you.