I tested it on a system or it was already installed. Installation (from the manual) is straightforward.
It is a transparent eq, but with a sound to fall. I'm surprised that nobody notices. I could compare this with eq almost anything that moves (limiting myself to eqs transparent: Sonnox, DMG Audio, FabFilter, Waves). The top is FabFilter and I saw (heard) no difference IIEQ pro. Same efficiency, musicality, same sound. The only differences are at the possibilities: FabFilter allows more customizable filters (6dB, 48dB), and treatments Stereo and M / S. But, again from his point of view, it's the same thing, just a fraction of the price.
I think for most people, this might serve as eq eq principal, for a ridiculous price.