I haven't read all the manga's, but from what I've read of the mangas and seen in the anime, this is one of the finest and truest conversions I've seen in a long time.

The show somehow creates a great sense of action without a ton of mecha and ninjas and also contains a lot of well crafted tension. This is an intelligent triller with some great characters which thankfully isn't full of anime clichés! As with most great shows, let alone animes, as the story progresses and more intriguing characters are introduced the quality rises and you become hooked.

I highly recommend checking out at least a few episodes to see how it sits with you. A lot of anime have a completely different feel from its peers and its worth giving some of them a chance to progress a little before dismissing them.