> I'm not yet sure if this is worth merging to master, so I'd
> very much appreciate opinions.

FWIW, I amnot in favor of it.  I'd prefer that users consult
the Isearch help for such info.

I have many more togglable options, and Emacs might in the
future also.

And there are many aspects regarding the current Isearch state
that it would be worthwhile indicating to users (either on an
ongoing basis or on demand, depending on the aspect of state).

The current value of a togglable variable, as well as the key
to toggle it, is info that falls in that category: it is part
of the current state.  I'd sooner see this info handled along
with other state info.  We've discussed this in other threads,
I believe.

----

FWIW, in my code I bind `C-h' to a modified version of
`isearch-mode-help' that not only shows the help but also 
exits Isearch.  I find that more useful than (a) requiring
`C-h m' and (b) keeping Isearch active.

Users need to be able to explore the *Help* buffer.  Especially
if there is a lot of info there, and in my version it lists
all of the Isearch bindings, in addition to showing the doc
string of `isearch-forward' (which in my case is longer).

I think it makes little sense to keep Isearch open during this
time.  It is trivial to restart Isearch.

FWIW, this is the definition I use, and bind to `C-h' in
`isearch-mode-map':

(defun isearch-mode-help ()
  "Display information on interactive search in buffer *Help*."
  (interactive)
  (describe-function 'isearch-forward)
  (isearch-done)
  (isearch-clean-overlays)
  (with-current-buffer "*Help*"
    (goto-char (point-max))
    (let ((buffer-read-only  nil)) (insert (substitute-command-keys "

Bindings in Isearch minor mode:
------------------------------

\\{isearch-mode-map}")))))

Attached is what *Help* shows for Isearch in my context.