After considerable deliberation & research in the optical compressor market, I gave this a whirl, primarily w/ a view to using in conjunction w/ an acoustic. It is VERY subtle tool & did not change or help fatten my acoustic tone as i had hoped ( the LR Baggs Session DI did!). I was also intrigued how it might work w/ my electric but again it was once again way too subtle for my taste so I reverted back to a modded BOSS CS3 (see my review). This pedal is a bit of a pain to power in that it requires an additional adaptor to a standard BOSS plug to operate. To install a battery you need to take the whole casing off & there is a tricky trim pot at the side of the unit to adjust input gain.
Not for me but I sold it on to a bass playing friend who says it is working out well for him so... :)