It does flange very well. Works best for in front of amp, not in effects loop since in the effects loop the effect feels attenuated somehow at least with my Marshall SV20H.
I would have liked the switch to click when pressed. It does not have that click sound or resistance when pressing. Would also preferred this to be smaller, more standard BOSS pedal size. It has only one flanger effect but didn't expect else from an analog pedal at this price point.
Overall, I think you will get excellent value for your money with this.