Nothing hits harder than this album when one's pissed off or overwhelmed with emotions and it works for me every time. It's an instant surge of energy, and before you know it the album's finished and you feel empowered.
There's not a single dud on here, there isn't even a song that's less memorable. Of course you have the metal anthem that is Walk, but the whole album is an anthem of metal spirit. Phil Anselmo is unmatched in gruff screams, with only John Bush (Armored Saint, Anthrax) coming close to the unhinged forcefulness. His lyrics are inspiring and speaking to the self-respect, self-confidence, individuality, and honor that I've always associated metal with. Dimebag is for good reason well respected for his solo skills, but also of note is how heavy of a sound he gives the band from being the only guitarist. Last but not least the rhythm section is among the best, it's just hook after hook and even during a solo there's something groovy in the background. Bassist Rex Brown has been a big influence on an approach to my own songwriting for thrash metal, as he basically gives his own rhythmic bass solo while Dimebag's doing his solos.
Also, it's possibly the album cover best representative of the music inside, just one forceful punch to the face that lasts for a fantastic 52 minutes. If asked to pick a top five albums of all time, this would definitely be one of those.