UI
Re: post 22 above, would you like me to attempt to make the category visible?
Or was the invisibility intentional?
Categorisation
Thanks. For me: in some ways the change is an improvement, in other ways it’s less user-friendly.
I performed some tests with Discourse on Android. Categorisation by default exposed a minor bug, I made the Discourse Team aware, the bug is acknowledged (also affected: Discourse on iOS).
That minor bug aside: a few other thoughts came to mind (I can share screenshots etc. in due course) but those thoughts are not yet firm.
It should become easier for people to get a ‘feel’ of the forum, on multiple platforms, after it gains momentum; after there’s more substantial content that is neither forum feedback, nor meta.
It may be worth spending a few days (just a few minutes each day) browsing and searching sites such as:
- Mozilla Discourse
- (I might add to this list at a later date).
At first glance, Mozilla’s use of Discourse is impressive. It is immediately obvious that great care and forethought has been given to organisation, and presentation, of categories and sub-categories.
For me, things became more thought-provoking when I scratched beneath the surface. In the handful of areas where I browsed or participated, I gained a sense that use of the forum for discussion is sometimes discouraged; there’s encouragement to use GitHub, not Discourse for discussion …
… which slightly defeats the object of a forum 
especially where reasons for setting up a forum include the perception that GitHub is not ideal for forum-like discussions (that’s a very broad topic … probably best continued in Discourse Meta, not here).
Cross reference: today’s illustrations by @jdittrich under First impressions (preview) – visualising how categories might appear with and without the rectangular logo requirement.