The attached pp.el patch does the following:

* Adds two user options used by `pp-eval-expression':
  `pp-eval-expression-print-length'
  `pp-eval-expression-print-level'

* Changes `pp-eval-expression' in these ways:

 . Respects the new options and `eval-expression-debug-on-error'. 

 . Reads the expression using keymap `pp-read-expression-map',
   which provides some Emacs-Lisp mode bindings.

 . Adds an optional arg INSERT-VALUE (prefix-arg), similar to
   what `eval-expression' has. See doc string.

I find it useful. YMMV.  I bind it to `M-:'. 

In minibuffer maps, I bind `M-:' to a command that calls this after binding
`enable-recursive-minibuffers' to t. With a negative prefix arg, I yank string
values (e.g. of variables) to the minibuffer (without double-quotes).