The format string parser is too simple.

[LosManos]

It only handles {0} and the like. What about escape sequence {{0}} and formatting like {0:dd}.

http://msdn.microsoft.com/en-us/library/txafckwd.aspx

Normal cases are handles anyway - the regular string.Format is always used.

[LosManos]

Isn't the format string parser outdated with inline $"strings" in C#?
Is there any situation the format string parser solves?
I suggest deprecating it.