I don't get why TOML is so underrated, it's barely mentioned in the HN discussion
Maybe it would be sense if quotation marks were not required for keys with only a restricted character set which are not an empty string, though.
“Hey, I deleted a character in a string and now I am getting this weird schema validation exception”.
They don't mention mismatched surrogates and otherwise invalid Unicode characters, but they should perhaps be implementation-dependent, like duplicate keys are. (It can either allow them or report an error.) There is also the possibility that some implementations may wish to disallow "\x00" or "\u0000" too, I think.
The thing I disagree is the part about white space. U+FEFF should be allowed only at the beginning of the document (optionally), and other than that only ASCII white space should be allowed. Unquoted keys also should be limited to ASCII characters.
Other than that, I think it is good.