You guys remember that Not-So-New Anime post I wrote? No? Oh, here it is.
Anyway, I finished one of the series: Btoom!
The worst part of the anime is that it's unfinished. There are only 12 episodes and the manga is ongoing. After one season, they apparently pulled the plug on the anime adaptation. This is the end shot.
It's rumored there may be another season, but no conformation yet that I can find.
So here's my final opinion: Read the manga if you're interested. I've read four chapters of it, just to make sure it's similar and it's almost the same. Things happen in a different order, but in the same way. All the characters also get more fleshed out and have backstories. I haven't got far enough to see if the whole rape thing is in it, but the first time we see the female lead there are the fan shots, so I'm guessing the attempted rapes will be in there too at some point.
I'm still interested in the series and how it will be resolved, so I'll be reading the manga until I hear word of a definate yes/no on the anime.