The Watchmen graphic novel is largely known as a watershed moment in the development of comics. Reading it twenty years later, this impact is largely lost, since nearly every major comic on the shelves today has been influenced by the gritty, dark, amoral qualities Alan Moore brought to his complex, alternate reality world.
The strength of the storytelling, though, does hold up. And Moore's problematic treatment of women is probably emphasized by the intervening twenty years, during which time more and more folks of the female persuasion have become involved in the comics world, both as readers and creators.
Perhaps most impressive is Moore's handling of the alternating flashback storyline, and the strongest section, narratively speaking, is Dr. Manhattan's reflections while on Mars. The structure of the story wanders, going from whodunit to a much more complex approach that in the end almost ignores the idea of the murder mystery.
The most problematic part of the book, though, is the female characters. Sally Jupiter's supposed "romance" with the Comedian is offensive to many, stemming as it does from an attempted rape. And Silk Spectre has little personality, her character largely defined by her relationships with Dr. Manhattan and Nite Owl. Visually, the ending is a bit jarring, and doesn't quite mesh with the "feel" of the rest of the book.
In spite of its flaws, though, Watchmen remains deserving of its status as a classic.