Recently I have been using git a little, and when pulling patches from
an upstream repository, it emits a summary similar to that produced by
the diffstat(1) command:

    Fast forward
     panels/midori-addons.c     |    2 ++
     panels/midori-console.c    |    9 ++++++---
     panels/midori-extensions.c |    2 ++
     3 files changed, 10 insertions(+), 3 deletions(-)

The diffstat style is to have one + for each added hunk, and one - for
each removed hunk.  This is useful as you can see at a glance which
files have a lot of changes, and which have only a few.  I think this
is easier to "see" than just the numbers.

This could be done for darcs --summary, too:

    $ darcs changes --last=1 --summary
    M ./GNUmakefile -12
    M ./configure.ac -9
    M ./darcs.cabal -16
    M ./src/Darcs/External.hs -31 +1

    $ darcs changes --last=1 --summary --diffstat
    M ./GNUmakefile		------------
    M ./configure.ac		-------------------
    M ./darcs.cabal		----------------
    M ./src/Darcs/External.hs	+-------------------------------

A demo patch would be useful so people can try it out.