For more of the original Watchmen GO HERE.
Even though the Watchmen universe is a great universe and Rorschach is one of my all-time favorite superheroes; Watchmen was enough. It had a main running philosophy that argued against those who would lie (utilitarianistically) so that people may be united. It pushed for the sharing of the truth (in order that people may choose to make their own decisions). It was a great story. I really liked the reality behind the heroes (it ran parallel to comic strips like Kick Ass and Marvel Noir) in this dimension. Even though I would love to see a comic series in a similar dimension with similar characters, these characters were meant to tell this story. They did. Job well done. The only reason I believe that they're coming back with prequels is to get people more excited about comic books (good) but mainly to make money (should not be a main driving point).
P.S. There's a whole different writer and everything, so the main plot/themes are probably scratched.
Concerning the Covers: Rorschach's cover is ok, this new guy looks dumb (and shouldn't be involved if not in the main Watchmen comic [they should have done Hooded Justice or Mothman]), Nite Owl would never be that lazy (he'd have more of a ready stance), the Comedian looks like the Comedian, Ozy's cover's probably the best, Silk Specter looks alright, the minutemen should have shown all of the members of the Minutemen (there are some cool ones including Mothman), Dr. Manhattan's cover looks inappropriate: