Bangle.js 2: How do I use it as delivered? Is there any user documentation?

Realistically compared with say the Pebble the UI is "horrible but serviceable"

This is true - the text menu especially, but that is something high up my list to work on so it should change soon :)

Some people may find installing https://banglejs.com/apps/#menusmall makes things nicer. Personally it's my preference right now, but it's not too friendly on the eyes!