@ Dagger IX1: I think that song is "Proof". It came with the Separation single.
I find SNF very addictive. Just the first episode makes me want to download more and more, following the story. The dialogues are nice overall, especially before each ED, which I believe is Soushi's voice. The characters in it are very well created. They're not just these emotionless animated drawings of people. They all have emotions and personalities. They're fun to analyze, specially Soushi, whom I like enough to make the avatar of. ^^
The background music are very well played, not very surprising because the Warsaw Philharmonic Orchestra are the ones playing. One of the things I love SNF is because it has a world-famous orchestra playing it's BGM's and Angela singing the OP and ED.
BTW, the OST is out and avaliable in BT if you search for it.