Supported: Doing an orchestral sketch with 4 choirs, no problem. And with 12 instruments I can spell out the full strings etc. Add in the portability of the iPad and this is a headline use case for me.
Unsupported: Doing a Zibaldone, which is a notebook for musical notes and nuggets you find in other pieces. Makes use of lots of text with staves. Since it looks like we can’t (yet?) have text frames this didn’t work out. Also I was trying to use @dankreider excellent MusAnalysis font for some roman numeral (which I hope/suspect will be in 4). It’s clumsy to get the font in the iPad, but I think it would work.