A very interesting concept, and one that, IMO, needed exploring in the Marvel Universe. The mutant underground, and their fight against humans. Their way is not Xavier's, and it isn't Magneto's. Their way is their own, and damn anyone who gets in their way. There are no superheroics in this, and like X-Force, I commend Marvel for trying something different.
The writing and art: I'll say I have NO clue who X is. I have a few guesses, but this issue doesn't lead me towards any of them. If it's Mackie, this is some of the best work. I'm looking forward to more, in all honesty. The art is also great. Conveys a dark underground feel to it, while still bearing a sense of reality to it. Like Seinkiewicz, but less abstract as that boy tends to get.
More to come.