I'd say it has the POTENTIAL to be a great story, but as many others have said, it needs to stick the landing.
There are a LOT of things that need to be resolved by story's end...and that will tell the tale.
Honestly if issue #12 isn't an oversized issue I'll be skeptical of whether John can pull it off.
If the resolution is:
-See issue #1 of LSH
-See issue #1 of JSA
-See upcoming issues of...
...I'll be disappointed. One of the beauties of the original Watchmen was it was a completely self-contained story.
So far D-Clock actually has been very self-contained which may be a great thing.