While there is considerable discussion over the question of whether the Watchmen movie is good, the answer ultimately lies in what you're looking for.
As a movie: See my review of the comics for more, but the story itself translates nicely. The concept is quite interesting, the mystery is highly captivating and the characters are well-developed. The acting is well-done, and the production values are generally high.
Cuts and Additions: In the process of transferring twelve chapters of comics into a movie, even a two and a half hour one, quite a bit had to be cut. Most of the supplemental material, such as the Under The Hood excerpts, and the Tales of the Black Freighter chapters are not shown or mentioned at all. Several interesting minor characters, like Dr. Malcolm Long and Hollis Mason have most of their scenes and development, which is unfortunate considering Watchmen's attention to detail. Most of the dialogue that is cut is relatively extraneous to the plot, but is often interesting and thought provoking, especially the Big Bad's explanation for his plan. The story does not change much from the excluded dialogue (although the evil plan is simplified and some characters' backstories are left unexplained), but it detracts from the experience.
Translating into the adaptation: Despite this, the creators manage to adapt the novel into movie form while preserving the original spirit, even if a considerable part of the material could not be included. Some parts would inevitably not translate well into a movie, like the Tales of the Black Freighter excerpts interspersed with the action, and the removal of some of the scenes helps streamline the narration and make it better fit for a movie. The opening montage helps show the changes in superheroes over time, with the song effectively speaking to the changing era and setting the tone for the movie. Some of the Bob Dylan songs that were referenced in the comic are included in the soundtrack, which is a nice touch if you've already read Watchmen. Despite the removed scenes, the movie remains a faithful adaptation of story.
If you're looking for an entertaining and thoughtful movie, you should see Watchmen and then read the graphic novel for the full story. If you've read Watchmen already, you should see it if you can open mind with regards to the changes.
The Movie: An Effective but Significantly Altered Adaptation For the Medium
While there is considerable discussion over the question of whether the Watchmen movie is good, the answer ultimately lies in what you're looking for.
As a movie: See my review of the comics for more, but the story itself translates nicely. The concept is quite interesting, the mystery is highly captivating and the characters are well-developed. The acting is well-done, and the production values are generally high.
Cuts and Additions: In the process of transferring twelve chapters of comics into a movie, even a two and a half hour one, quite a bit had to be cut. Most of the supplemental material, such as the Under The Hood excerpts, and the Tales of the Black Freighter chapters are not shown or mentioned at all. Several interesting minor characters, like Dr. Malcolm Long and Hollis Mason have most of their scenes and development, which is unfortunate considering Watchmen's attention to detail. Most of the dialogue that is cut is relatively extraneous to the plot, but is often interesting and thought provoking, especially the Big Bad's explanation for his plan. The story does not change much from the excluded dialogue (although the evil plan is simplified and some characters' backstories are left unexplained), but it detracts from the experience.
Translating into the adaptation: Despite this, the creators manage to adapt the novel into movie form while preserving the original spirit, even if a considerable part of the material could not be included. Some parts would inevitably not translate well into a movie, like the Tales of the Black Freighter excerpts interspersed with the action, and the removal of some of the scenes helps streamline the narration and make it better fit for a movie. The opening montage helps show the changes in superheroes over time, with the song effectively speaking to the changing era and setting the tone for the movie. Some of the Bob Dylan songs that were referenced in the comic are included in the soundtrack, which is a nice touch if you've already read Watchmen. Despite the removed scenes, the movie remains a faithful adaptation of story.
If you're looking for an entertaining and thoughtful movie, you should see Watchmen and then read the graphic novel for the full story. If you've read Watchmen already, you should see it if you can open mind with regards to the changes.