A very solid 4/5.
Generally speaking this a worthwhile app that is capable of adding a lot of character to a track and in a variety of genres - I’ve used it with good results on a dance track, a reggae tune, and a pop ballad and it was versatile enough to help fill out otherwise minimalist songs. The interface isn’t my favorite, although it’s mostly serviceable. Would also like to see more developed editing capabilities for making slight tweaks to a generated arrangement in the app (so I’m not trying to achieve them with destructive edits afterwards.) That said: besides its sister app there’s really nothing else close afaik in iOS music world.