He was no virtuoso, and that's the whole point: By snatching electric guitar from note-shredding technicians and giving it back to artists, freaks and poets, Kurt Cobain became one of the most important players ever. Cobain didn't invent alt-rock. But with his love of Cheap Trick, the Melvins and Kiss, he gave it the metallic power necessary to conquer the world. His playing wasn't all untutored squall, either: See the unconventional chord progression and mastery of quiet-loud-quiet dynamics on "Lithium" – and pretty much every other Nirvana song.
When Kurt Cobain hit the stage, it was very often with a Fender Mustang guitar—an enigmatic anti-hero figure with an esoteric anti-hero instrument. The Fender Mustang evokes the man, the band, the sound and the times.
Kurt Cobain liked Mustang guitars a lot. For one, he preferred offbeat guitars that didn't cost zillions of dollars, and the Mustang certainly fit those two criteria. Also, being somewhat physically diminutive himself, he liked to perform live with slightly more diminutive guitars, like the Mustang and Jaguar guitar, which better fit his hands and his reach.