Electro Harmonix Pico Swello

The Pico Swello replaces my old EX Attack Delay, and it’s a major improvement. The polyphonic mode on the Attack Delay always left artefacts and slightly altered the tone — sometimes adding a metallic edge that became distracting. The Pico Swello has none of these issues. It tracks cleanly and responds quickly, so even fast guitar passages are smoothed without glitching. The effect is genuinely impressive: it can turn your guitar into something that feels almost like a bowed instrument, giving you violin-like swells or a fluid, steel-string texture with ease

Very inspiring pedal, doing well what it's supposed to! Slow attacks, very useful for ambient swells and good tracking for faster playing. It really helps to extend guitar playing possibilities.
I would prefer an even slower attack time. Also, when the filter is off there is still some colorization of the tone.