Great for taking and organizing notes (better yet if you use Zettelkasten methods). Excellent (really) for writing academic texts which will be converted (with e.g. Pandoc) to PDF or other formats.
With Zettlr (plus Zotero or other reference manager exporting library to CSL JSON), citing is incredibly simple: configure where is your citation library, and then just type '@' and it will show ALL your cites for you to choose.
Seriously, I wrote my entire Master's thesis on it last year. Images preview, UI theming, all that simple citing, and a program that keeps out of your way to work. It's great, and, best of all, open source.
Suggestion of companion open source apps/programs for academic writing:
- Zotero: for managing your citations
- Pandoc: for converting your text to DOCX or ODT, or PDF directly (with some TeX engine)
- Git: to revision and version your changes to text