he's writing a boatload of characters i never really cared about, and finds a way to get me to read them and want to know more about them. and no batman! that, alone, is a huge challenge.
and, really, from what i've heard, even long time fans of the characters in question appreciate his work.
that, really, is the major undertaking all of today's writers have in front of them -- to be able to please most of the older fans, most of the newer fans, and pull in not-yet fans. and, to his credit, i think he's really done a great frickin job of that.
scouring through the jsa or flash (etc, etc) forums, i see lots and lots of happy fans and happy fanboys (and girls).
while he might not be my personal favorite writer (i said "no batman"), id easily rank him as one of today's greatest