Ranked in these QuestionsQuestion Ranking
Pro Extremely lightweight (55 kb)
Pro Rich set of plugins
Pro Has a great wiki
Pro Minimal configuration with sane defaults
Default options and navigation is simple to grasp.
Pro Unique navigate-as-you-type mode
Pro Awesome new features being added in every release
Pro Integrates with the desktop environment and opens files in the default applications
Save and resume sessions.
Pro Supports cd-on-quit
Allows for quick switching between nnn and the terminal.
Pro Reasonably well-documented
However, it requires some prior knowledge of inner workings of Linux and there are no tutorials (yet). NNN author is making up for this by actively responding to GitHub issues.
The file manager has recently added support for preview hovered files using various methods.