A lot of people have a testy relationship with Alan Moore, myself included (depending on his work; I've never been a big fan of League of Extraordinary Gentlemen). But, uh, let's not get into the Watchmen ending discussion/argument again, please? We've had it multiple times on the forums and it boils down to some people prefer the book ending (like myself) and some prefer the movie ending.
It's funny, though. When it comes to adaptations, I've become a lot more open minded and ambivalent towards changes. I think about an interview I saw once with Steven Gould. They asked him how he felt about all the changes they made to his book, Jumper (which was a so-so to solid, but not great action flick). He turned around in his library and pointed to his shelf. "Do you see the book up there? I can pull it down at any time and read it exactly how it was when it was published. They haven't changed a thing about it."
I think about adaptations like Scott Pilgrim or What Dreams May Come, where both the comic/book and the movie are great for entirely different reasons. "Changes" made in superhero adaptions never bother me anymore since the comics have had so many flipping iterations of the same iconic characters that there's very few mainstays in the story, aside from the bare bones basics.
Yet, for some reason, I still can't have that same open mind with V for Vendetta or especially Watchmen. Honestly, I'm really not sure what it is about those that I can't accept as well. Watchmen looked great, like it was taken right out of the comic. And for all the things they got right, they got really right (Rorschach; which really, if you screw him up, you shouldn't bother making the movie). But for all the things they got wrong, they got them really wrong (Silk Spectre, the softcore porn scene, the ending). It's not even a bad movie by any means, but I've just never been able to come to terms with the changes for some unknown reason.
