TOML is an underrated file format.

TOML is a good file format for the goals it was designed to accomplish.

TOML aims to be a minimal configuration file format that's easy to read due to obvious semantics.

I believe it fulfills this goal pretty well; but it gets so much criticism for goals that it isn't designed to accomplish, or goals that are impossible to fulfill (e.g "not being simple enough").

I like the datetime type; they allow developers to use a datetime system without having to maintain their own datetime library.