First off, I'm really enjoying the app so far. Definitely gonna be using this over Audacity for the foreseeable future.
There are however two features that I think could really benefit the workflow, at least for me. Both are about adding greater editing potential to the default track-preview.
1. Being able to fade-in and -out the track. Ideally it would be done in a very intuitive and easy way, like being able to CTRL-drag from the edges of your current selection to define the fading period.
2. Adding Track Effects. Similarly to 1, this would mostly serve not having to switch to the multitrack view when you just want to apply an effect to a single track. Additionally, this could come in very handy if you want to apply the same effect to multiple tracks in your library, assuming there is some option to preserve your current effects setup while switching between different tracks.