The best feature of the eTAP is the number of excellent presets for approximating a variety of vintage tape machines. Most of the presets are low feedback and help to increase the density of a drum loop or add a nice tape slapback sort of sound to guitar. However, it's easy enough to midi learn the feedback knob for more extreme effects and play with those in real time.
The sound of the delays is free of digital artifacts even when changing settings; the knobs are smooth and could be manipulated in real time. It sounds convincing in a mix with physical instruments (e.g., live drums, guitars, etc.). Because the saturation and tape wow can be controlled by the user, it's quite useful for nice clean delays or for grittier broken down tape machine effects.