Daniel Bachhuber has just published the results of the first WP-CLI user survey. The results should provide some guidance for Daniel and others working on the project, as they shed some light on how people are using WP-CLI, and perhaps some features that may be under-utilized, such as community packages. Predictably, the most common uses cases are installing, updating, and migrating WordPress.
Many respondents requested better documentation. Conveniently, all of the docs are generated from the source code, so if you use WP-CLI, consider submitting a pull request to improve the current documentation.
My personal plea to Daniel: add a wp make bacon
command.