I see a lot of people being mad about the ambiance, the pantyshots, the "hentaiborder", Claire's weird character etc...
But in the end, the manga is all about that uneasy feeling. You can either accept it and love it, or hate it. You can't rate a manga based on your preferences only. The art is great the synopsis is good (a little cliché i'll give you that) and the writing sometimes gets out of control but it's weird. Most masterpieces are weird. The mainstream ones sure are familyfriendly, but evangelion, made in abyss, ergo proxy etc... it's their aura that made them so good.

"It just works"
Todd Howard, 400 b.C.