Yeah, so as everyone else has said, Aphorism is really the kind of series that you have to employ a certain amount of suspension of disbelief as the premise is so utterly laughable. After you get past the original necessary brain shut-down, however, Aphorism actually becomes quite enjoyable.
Aphorism is, in short, a series that is going for something utterly original, never mind that, even on a fantasy-level, the idea seems very, very dubious. Now, once you get past the "dubious" part, you have got yourself some nice, gory horror-action with a bit of mystery on the side. It's all very interesting and entertaining, actually, and I find myself looking forward to each new chapter more and more.
The characters are decent. They have somewhat more personality than the traditional shounen heroes (in other words, I can't really sum up their personalities in only one word), and none of them are a particular hardship to watch.
And, the gore, while definitely not on the level of seinen, is quite a bit more graphic than traditional shounens, which I appreciate, the art is really nice, and the paneling is not at all confusing. What more can you ask for, really? (Well, other than a believable premise, but we've been over that already.)
In short, Aphorism is great for a casual read. It isn't anything particularly life-changing, but if you love blood and gore and action to go along with it, this is certainly a worthwhile series to invest your time in.