I'm suprised you rated the feature this highly. While I haven't seen it yet, even in the original comic the black freighter story was a little more than filler for the issues. I'm sure some would argue that it was in there to relate the horrors that are happening in the comic with those in the "real world" (by that I mean the watchemen comic itself) but those people read way to much into things and should get a life.
Personally I'm not a fan of the sub-story at all as it was generic and far too predicatable. Considering its only 20 min long and they STILL managed to change things around (for the worse apparently) this is nothing more than a cheap tie-in gimmick and such gimmicks should get an automatic 0 out of 5, just for the intent of ripping people off.