On one level, given the current political climate, this was a daring movie to make (with its pro-anarchist / terrorist bent). However, I wish they would have followed Alan Moore's vision from the comic book series more closely. The directing and story rewrite are both clumsy, leading to a film which is badly paced and lacks the depth of the original comic vision.
As with many superhero movies, this movie is cast as the story of a man, V. I didn't like how aggressively the movie set this up as his story, given that the comic is really about a number of different important characters and how they react to and come to grips with climbing out of a totalitarian England into something wilder and freer. V, in wearing a mask and always spouting the quotes of others is very much an anti-individual, representing instead ideas and symbolic roles rather than an egoistic role in the narrative, so the story of a man angle didn't really work for me. The ending, where everyone is wearing the V mask in an "I am Spartacus" kind of moment felt particularly like a Hollywood cliché.
Also, despite the claims made in the commercials for the movie that this is an 'uncompromising' vision of the future, quite a few things have been sanitized from the comic version. Evey starts out not as a street urchin offering her body for money, but instead as a government office worker unluckily trapped out after curfew. V's speech is cleaned up quite a bit, so despite some hyper eloquent patches in the beginning of the movie, he does not have as unique a voice as in the comic. Lots of strange bits of the comic are left out as well, such as the leader's psychosexual fascination with Fate, the computer in the comic that essentially runs the government (left out completely from the movie).
The world is clumsily constructed, especially as compared to the comic series. Though the thug characters are described as Fingermen, the movie never explains that there are the different government agencies of the Nose, the Eye, the Ear, etc. The overall process whereby V dismantles the government's credibility is reordered in the movie, and coupled with the lack of explanation about how the government is setup makes the story less coherent or believable.
Lastly, and most importantly in my mind, the film totally botches the part of the story where V incarcerates Evey while tricking her into thinking she is being held by the government. In the comic, the incarceration is more brutal, and the reveal is spookier and more troubling. Valerie's letter, one of the more beautiful bits of prose in modern comics, gets lost in the movie as the interspersing of the text of the letter with images of captivity is done rather weakly. Perhaps the intertextual play possible in comics, and handled most superbly by Alan Moore, just doesn't work in film. However, in this case, it felt more like a directing problem than a limitation of the medium.
If you haven't already, please read the comic. If you just see the movie you'll lose out on the powerful vision and voice that Alan Moore constructed to problematize the safety of contemporary society.