I think The Watchmen will eventually be more appreciated than it is. Outstanding casting. I think it is a work of art. Yes it has a different ending. I think of the graphic novel as a storyboard. Don't fault the final product just because it was revised from the storyboard version.
I have mixed feelings on Watchmen.
At one point, I'm glad they did it. I think it was a valiant effort and a good deal of the story remains intact and they were able to keep many of the key parts of the story that made the story great.
But, I think so much of what made Watchmen a great book get's lost in Snyder's style. Too much of the movie is wrapped up in Snyder doing what Snyder does and so much attention to the 'look' that the story and parts of it are lost... I never got a sense of tension or that something was building throughout the film... just seemed to condensed, maybe they tried too much? ...and yeah, no Bubastis and the new ending took a bit out of the film as well (the latter much more than the former).
Ultimately, it's a flawed movie that I will watch and enjoy from time to time. ...and yeah, it was left a tad underappreciated by the general audience.
And I'll always wonder how it would've played out as premium cable TV Mini-series. This could've been an amazing 12 part/hour mini-series...
Ebert gave it 4 stars, and it gets a 7.7 on the iMDB - so it definitely was appreciated by some... just never really found an audience.