This album kicks a**.  The music is hard-driving, complex, and deeply layered with powerful emotional lyrics and ethereal *headroom*.  I'm a LONG-time fan of progressive and avant-garde rock (e.g. Captain Beefheart, King Crimson, early Pink Floyd, etc.) and Tool combines the artful legacy of those groups with the head-banging thrill of more modern fare.  If you haven't heard anything from this group you owe it to yourself to spend the $10 (or so) and take a chance.  Especially so if any of the above strikes a chord with you.