Wow! That is the word that came to mind when I heard this. Unquestionable Presence came out in 1991, the same year as Death-Human and Meshuggah-Contradictions Collapse. Clearly, change was in the air at this time. Bands were trying new things, and metal was becoming more complex and sophisticated. Though sometimes overlooked, Atheist was a pioneering force in this movement. Each song on this album is like a festival of great riffs, alternating between harmonized twin guitar parts and utterly delicious thrash/speed metal sections. The vocals are primitive screams that vary in intensity, sounding like a full-fledged snarl most of the time, but almost like a speaking voice in some parts. Forget all the arguments about pointless technicality with no direction, because this is technical music that really takes you somewhere. Complex arrangements, stop and start riffing, dual guitar harmonies, fluid solos, technical drumming, integral bass guitar action. The songs seem to evolve naturally, with each new riff sounding like the most logical progression from the last.