Electro Harmonix Pico Atomic Cluster

Although it's a good idea and chaos is part of it, there is an auto-wah effect going on that produces a constant mid low sound that lowers the overall tone. Handling is also not its strong point as Dynamics mode could get your ear pierced and tracking is weird even for a synth pedal. Maybe it's not working polyphonic as expected.
I returned it since it was difficult to produce a somehow stable chaotic sound like I had it in my mind. I would like this idea to get better first before buying a similar pedal again.

I never thought I’d get R2D2 out of my amp, but there you go!
It’s an interesting little pedal, with some lovely sounds emanating from it. I need more time to explore the full complexities, but so far very pleased with it.

Really sounds good, but under curtain circumstances and in the right place in your FX chain. I've used it with guitars and synths.