My first impression of this album is that it is unlike her earlier work. The melodies are minimal, comprised more of specific sounds and "blip" and "bleep" noises rather than smooth melodic passages. Rhythmically, it seems uncomplicated, relying on very basic beats, often midtempo or even slow.
I've always thought of Ellen Allien's music as listener-oriented techno and not just specifically for dancing. Sool makes this style even more obvious, as few tracks feel really dancable. Pop elements are few on this album; it is truly electronic music. Vocals are scant, chorus are nearly completely gone. Instead, it is subtle and challenging, demanding the listener's attention and making repeat listens absolutely necessary to fully comprehend what is going on in these songs. It is not immediate or urgent.
Sool makes good use of ambience and atmosphere, branching more into micro-house and IDM territory and leaving behind the clubby techno of songs like "The Brain Is Lost" (from Thrills), "Sehnsucht" (from Berlinette) and certainly "Rotary" (from the collaboration with Apparat, Orchestra Of Bubbles). The dance music isn't totally lost, as heard in "Its" and "MM," but it has changed from what it was on earlier albums. The melodies have lost fluidity and become quiet, in contrast to the more legato and loud tracks from Thrills.
The dance floor is not the place for an album like Sool, because Ellen Allien has branched out, daring to slow things down and make more complex music art rather than fodder for body moving (not to insult dance music, but this album just isn't that). Headphones would be more appropriate for this album, for its minimal, micro-house/IDM leanings are for audience craving interesting electronic music.