" It seems though to be really not well known...but it needs to be! "I doubt the general public or someone new to anime is aware of it, but it's pretty well known for fans of a certain age group or with more anime watching experience. I think the type of fan who is aware of shows like Noir, Paranoia Agent, Witch Hunter Robin, Lain and to a lesser extent Gunslinger Girl are probably aware of HR.
One of the things I liked about Haibane Renmei is that unlike shows such as Utena, RahXephon, Wolf's Rain, etc., you can shrug off all of the symbolic aspects and still enjoy the story. It's also not like Evangelion or Lain where you know there's this philosophy being shoved down your throat; I prefer the subliminal approach because it's more rewarding and much harder to do. At first I thought the characters were kind of forgettable, but the friendship between Rakka and Reki was really captivating, and the characterization was subtle but strong. I'm not sure how heavily based in Christianity it was, but I loved the themes about forgiveness, flight, and freedom. The bird and cardinal direction imagery was really well done as well. I need to revisit the show; I've only seen it once and it's worth a second look.