Eh, not sure I like it. For this to work, they have to make the indentation part of the syntax. Otherwise stuff is way too ambiguous to infer the correct parenthesis. A result is that the programmer has to be intimately familiar with how the inference works and what the syntax of indentation is. I feel that this just shifts cognitive load from managing parenthesis to managing indentation and inference. From the documentation:

  The rules for what happens when inserting/deleting parens must be
  learned. Also, the case necessitating a "Paren Mode" comes at the
  cost of forcing the user to understand when and how to switch
  editing modes.
  
  Also, the preprocessor step performed when opening files will cause
  more formatting-related changes in your commit history when
  collaborating with others not using Parinfer.