No, not Hentai in the least. But it is very adult. However I think it works perfectly, and the art style is also very appropriate.
AFAIK, all the Marvel MAX comics are done by the same writer/artist crew (Garth Ennis writing, I don't know who's drawing). They come in nice 6 comic story lines, which I also love. Basically, its all the Marvel badasses with the kiddy gloves taken off (Nick Fury for example).
I would reccomend it to anyone even remotely interested in comics. Granted, its not going to change your life or anything, but it is a nice alternative to spandex-clad do-gooders.