Simoun/YMMV

Come for the X, Stay for the Y: Many cases of: "Come for the yuri, stay for the well-written War Drama and awesome music."
Complete Monster: The Defense Minister of Simulacrum.
Ensemble Darkhorse: Yun, Mamiina, and Rodoreamon have become the undisputed fan favourites, as has their subplot in general.
Fetish Fuel Station Attendant: Dominura. Her name alone is Fetish Fuel.
Funny Aneurysm Moment: Angulas' refusal to say Aaeru's name when introduced to her was kind of amusing, right? Not so much when they reveal why...
Genre Turning Point: What Yami to Boushi to Hon no Tabibito and Kannazuki no Miko did for popular acclaim of Yuri anime, Simoun did for critical acclaim.
Narm Charm: Simoun is sometimes cited as having one of the greatest climaxes in the history of anime: the Heel Faith Turn of the Plumbish nation. It is so great partly because it is so overblown and melodramatic. See the concept of 'eucatastrophe' (first described by JRR Tolkien) for more on this.
Nightmare Fuel: In the second episode, after visiting the Spring for her gender assignment, one of the former Sibyllae of Chor Tempest leaves with this devastated look on her face. She starts to cry, and then collapses amid screaming tears. Since she still couldn't make up her mind after entering the spring, it chose for her.
Spiritual Licensee: It can be described as an anime version of A Canticle for Leibowitz. With added Les Yay.
Subbing Versus Dubbing: Actually, more of a Subbing Versus Other Subbing. With a two year delay between its airing in Japan and its DVD release in North America (Although incredibly fast when compared to some other Anime) there was already a fansub circulating on-line (and a few episodes' worth of a second) before an official version was presented. None differ from the others in any significant ways, but neither can any agree on the proper ways to spell the characters names, and there are many different ways to "really" translate certain sentences.
The Woobie: Neviril, Rodoreamon, Paraietta.