I just started getting into this rather prolific band. If you haven't heard of them, Melvins are a four-piece grunge/sludge act from Washington (no surprise there). They've been jamming since the late 80s and are still releasing new material. They cite Black Flag, Black Sabbath, Swans, and Flipper as influences, but they really have a pretty unique sound that can't really be fully defined. Bands like Nirvana and Soundgarden worshiped them. It's safe to say that Melvins had a strong influence on the whole grunge scene.
For this particular album, Cobain helped produce several tracks and even played some instruments on some of them. This is Melvins supposedly at their most accessible. That being said, it's still pretty strange.
Disclaimer: You know the deal.