Notch filter: very good. EQ: good. High pass filter: very good.
Gain : decent. 6db are not enough to make it a preamp. This pedal is not a preamp, be warned. Volume: only a few db.
I think it is an all-in-one pedal for acoustics doing the most important things: notch, eq, hipass, phase, and with a limited volume control.
Very high quality, worth the price for sure.