All music of this Original Soundtrack have been composed and produced by SAWANO Hiroyuki (Aldnoah.Zero, Blue Exorcist, Kill la Kill, Zombie-Loan, Guilty Crown). It contains 10 BGM & 6 vocals ; and gathers different music styles, such as: electronic, orchestral, classical and rock jazz. The instruments mostly used are keyboards & piano ; as well as drums, bass, guitars, strings, trumpet and horns.
The entire album is very excellent (not to say epic!), even for those who have not yet seen the anime serie. It is anything but boring. The most of tracks are electro-orchestral music and rock as well. Furthermore, the songs (n°1, 2, 7, 8, 12, 15) are really good, especially those sung by KOBAYASHI Mika: "Attack on titan" (n°1), from 2'25" you can hear one of the most epic part of this album, the Mika's voice is so powerfull and beautifull in the same time ; "Bauklotze" (n°12), is the slow and accoustic version of the main theme "Attack on Titan", just amazing! The song "Vogel im kafig" (n°7), sung by cyua, is absolutely beautiful as well. The best parts is, to me, at 1'42" and at 4'45", so powerful and heavenly!
Regarding BGM, my favorites ones are: "Eye-water" (n°3), melancholic, soft and purified music played with piano ; "Rittai kidou" (n°4), epic theme played a number of times in the serie (before the battle scene), sounds like a martial music; "Counter.attack-mankind" (n°5), another epic theme divided here into two parts: the first one is pretty wonderful, I really like this electro-orchestral music, especially for those intruments (strings, guitar, french horns) ; the second part (from 3'04") is used for fighting scene, it is an electronic music with a lot of tensions accompanied by french horns, percussions and chorus. Really good. In the same style, we have "Xl-tt" (n°14), still with chorus, horns and percussions (and church bell sounds from 6'05").
Anyway, an abum to listen to urgently! Whether it be BGM or vocals, all tracks are magnificent.