Eden has held a conspicuous spot in my personal top 5 since I first came across it. Scope of the story is ambitious, to say the least ... post-apocalyptic bioterror mafia epic is not the most copious genre out there, but damned if Eden doesn't make it one of the best-represented. Lots of surprises, as well (I'd call the story anything but predictable). Just the fact that characters in whom we have some sympathetic interest get killed/maimed on a regular basis is enough to keep you from ever getting too comfy with things, and the plot takes plenty of creative turns in its own right.
I wouldn't call the violence in Eden gratuitous, but it is extraordinarily graphic. To me, this builds out another aspect of an unusually acute reading experience, but some might find it heavy.
Aside from the predictability thing, have to take issue with two other points made by Chas below. One, I don't see the manga taking "an obvious stance in what's considered right and wrong" ... every single character in it is morally compromised. We have sympathetic allegiances to some of them, as in any story, but there are no "good" guys here. Governments are not paragons of virtue; underworld power brokers are not paragons of virtue; regular people trying to get by in the rough-and-tumble of society are not paragons of virtue. Chas is saying, I guess, that some governments are "good" (i.e., it's the identity of these that he wants to decide for himself) ... but then who's being unrealistic?
Second, his comments about the storytelling pretty much condemn themselves, but it's worth calling them out. "Basically, it plops you down in the middle of the story, without really revealing much of the background information of the characters" --- yes, this is called "in medias res" plot development, noted as one of the hallmarks of literary mastery in Shakespeare and Homer, for example. Eden isn't literature on that scale, but it is one of the more skilfully told stories in manga, for damn sure. There are a few (not very many, honestly) timeframe jumps that require you to pay attention, but well-crafted non-linear storytelling is again usually counted a bonus by those who appreciate a good read. As to whether there are "huge holes" in the story --- shouldn't that be decided after it's finished? Seriously, is there a page limit within which complex developing threads are required to be tied up? If you insist on straightahead plot with orderly introductions of characters and prompt resolution of episodes, Marmalade Boy is pretty good (and no worries, its depiction of early-90's ice-cream-scoop technology is scrupulously realistic) ...
I've just finished the series, and came back to update my rating and my comment. Because my earlier comment was part of a larger conversation, I'm leaving it as is (above). It's also useful to see what I was thinking back around volume 10 or so. My final thoughts follow ... some quasi-spolier stuff is in there, so be warned.
In the end, I thought the manga didn't quite live up to the promise of the first 8-9 volumes. That opening half was masterful, and I was definitely willing to give Endo a lot of leeway to develop things as he saw fit in the second half; but despite some moments of brilliance, this latter part didn't have the same effect on me. I would put that down chiefly to
- long digressions into the lives of characters who, in the end, only tie back into the main story when everyone gets together for the final resolution (and then sometimes only at second- or third-hand); I was hoping for an integral weaving together of threads along the lines of what we saw in the opening half.
- a panning away from a story focused on the lives of Eliah and Ennoia, to one about the whole human race as a race, which leaves me just a little bit ... meh.
Honestly, this looks like a case of the classic Sudden-Editorial-Cancellation-and-Hasty-Wrap-Up problem; but if there was a cancellation, it probably owes a lot to the minor-character-digressions that seem to take over the action at a certain point.
Still a great read, still worth your time (when it's great it's really great), but I'm downgrading from a 10 to a 9. Sincere thanks to all who've worked to make Eden accessible to English readers over the last many years.