I was a big fan of the Deadman Wonderland anime and really did crave more since finishing the short season. I decided to give the manga a go and if you are in the same boat, I would recommend reading from chapter 1. The anime leaves out a lot (including one of the most important details) and doesn't introduce you to all the characters. This is absolutely an instance where I would say the manga is superior to the anime adaptation.
The manga is split into three arcs. The anime covers the first. I enjoyed all three of them as much as I did initially watching the anime. It's very exciting, has fine pacing and is a very enjoyable although somewhat depressing experience to read!