Finally got around to re-reading the whole thing.
Eden is great. The art, characters (+development), delivery, and plot are some of the best I've encountered in manga (though not the best, hence the 9).
I feel like Eden started off very very strong, faltered in the middle, and the ending was slightly forgettable. Definitely biased since I personally adore plots with time frame jumps that come together as more information comes to light.
I feel like the emotions were very poignant in the first few volumes - the lines were brilliant and the delivery was almost flawless. It was so good that I put my rose-colored glasses on and ignored the first few missteps later on. Somewhere in the middle (during the arc when Miriam was introduced, I think) I stopped feeling that way, because the story became more about mafia back-stabbing and delving into the darkness of society, but with Eliah being completely weird with his humor. Sorry Endou, but that premise has been well-explored and you didn't really bring anything new to the table.
Then somehow it jumped back into the thought-provoking time frame jumps, but still, it was less heartfelt than before. Maybe I've just watched too many documentaries, but all talking about all those world issues without an intensely personal story weaved in was a bit bland. It sort of redeemed itself because it put in all those allusions to Gnosticism, which I've read a lot about, so I felt like I got more out of it than Endou intended because I was reading too much into everything. The ending definitely could have been delivered in a better way, and the message could've had so much more impact. But at least there was a sense of closure, which was nice.
So there you go, another wall of text about Eden. XD Read it, it's definitely one of the better mangas out there!