twin pitch shifters modulating across 6 modes...it sounds a bit like an Arpanoid, Rainbow Machine, and a Digitech Whammy in one box...but add some background trem throb.
The product page explains the pitch-tracking and features like 4 onboard presets (but only 16 via MIDI?). Not a new experience per say, but quirky fun in a compact format. For people who only need these types of sounds on a few tracks, it's a more-budget friendly option than buying 4-5 separate pedals.
https://www.alexanderpedals.com/shop/marshmallow
http://www.youtube.com/watch?v=QYYBsgfkLfw
http://www.youtube.com/watch?v=uO7zCUrD03Y