I like that it's simple to use, very customizable (you can create your own themes), has great support for languages such as JavaScript/TypeScript and HTML5 templates (which are my favorite).
The only thing I don't really like is that they've not done much work on making the theme editor even better. Maybe there should be more options when editing color schemes? It could also maybe have an export option so that you don't need to manually edit each file every time you update a new version? That way, if we ever want to revert back to an older version we would still have our old files which were edited by us. We're using this plugin to make it easier for people to view our website code.