The ability to forge powerful and emotionally evocative music with as little instrumentation and texture as possible. To create something starkly minimal and elegant that is also overwhelming and encapsulating. This is what Slint managed so well with "Spiderland". They stripped traditional rock formats to extreme basics, creating one of the most important contemporary albums.
"Spiderland" is often labelled as one of the very first post-rock albums. There is certainly the stark dynamic shifts akin to the genre, with songs often starting out as single guitar motifs and ending as full-on assaults. The vocals drift between soft whispers, spoken word and frustrated croons. However, "Spiderland" is much more than today's often generic post-rock sound. The guitars are gritty and far more visceral than anything Mogwai or GY!BE would ever belt out, and often progress into full-on riffs. It's atmospheric, but in an intensely sombre way that goes beyond much of the disposable noodling found in modern post-rock. Perhaps then it is just what post-rock should be. It should be beautiful music that can be at once fragile and on the brink of falling apart, and switch to absolute bombastic power.
There really isn't a weak track, and the songs tend to follow similar patterns and structuring - and so I don't feel it necessary to pick apart every song as some fans have done. To be concise, "Spiderland" is the perfect deconstruction of rock - it manages to be abrasive and confrontational, yet unadorned and delicate.