Instruct: Classify Amazon reviews into positive or negative sentiment
Query: super-intense and challenging.

This is an extremely complex album, probably the most musically demanding progressive/prog metal album aside from Garden Wall's _Forget the Colours_. Spiral Architect's profound technical excursions are voxtex-generating maelstroms of staggered, sycnopated razors rhythms interacting in an abstruse, hyper-complex manner both intensely Dionysian and Apollonian. Polymeter and displacement, odd articulation, and very unusual structures (much more challenging to play than to hear) are the tip of the iceberg for this band's unbelievably insane music. The vocals are high-pitched prog metal style vocals which sound a little off at times, but the way he sings really fits so it's all good. Check it out or shame on you. And hey, anything where Sean Malone contributes is automatically amazing (even if it's only on a brief instrumental interlude). _A Sceptic's Universe_ [sic] is essential.