...: execution time, returned/affected rows, excerpts of the found rows, error messages, etc. It also automatically EXPLAIN's each SELECT query (so you don't miss those keys again!).
It encourages developers to write maintainable code and provides a better default security layer by encouraging the use of prepared statements, where parameters are automatically escaped.
Code is heavily commented and generates no warnings/errors/notices when PHP's error reporting level is set to E_ALL