Incredible for guitar & bass
If you can only have one dirt pedal, this thing would keep you satisfied. This is everything you expect from a great OD pedal and the dual-gain / alchemy feature gives it a lot of range. As you crank it up, it easily gets into distortion territory (like an Fulltone OCD, for example), but does not get insane like a MetalZone or Fuzz pedal.
My favorite thing about this pedal is the attack. It has a really crisp bite even at full gain, and plays nicely when I send it into other overdrives. I can also get this to overdrive by bass and bass amp wonderfully, but expect a drop in low-end. The alchemy (blender knob) feature is awesome because you can set one gain high and the other low, and get some very unique grit sounds blending them. Think the intro of "Drown" by The Smashing Pumpkins - clean sizzle!