I haven't listened to enough of Kurt Cobain's music to critique the artwork from that viewpoint. I'm familiar with "All Apologies" and a couple of Nirvana's other big hits, but that's all. I suppose the dark tones of the painting coordinates nicely with the flat-tuning for which they are known.

Portions of your artwork, though are definitely fascinating. I love the detail half-way down the left side, which reminds me of green shrubs/trees reaching up into a sunset sky with the Moon hanging there. And the detail from lower left looks like a pathway lined by trees with autumn colors! Very pretty!