For me, this was not an improvement on the book. The book is flawed, the first act were most of the vengeance takes place, is particularly pulpy, and shows it's episodic origins from I think 2000AD
It was in part 2 and 3 of the book that it became more than it's origins, and it was in this part of the film that it started to loose it's charms. I had no problem with the shuffling of events, and the illimination of the party overflow plot, as I understand that they streamlined the film to concentrate on V and Evey. IIRC, V pretty much dissapears from the novel for all of act 2 (the Evey shacked up with the fingerman/ rouge elements take over subplot), after his TV message and shutting down the security cameras so that the people of England could have a real sense of freedom.
The masks were a purly cinematic device, which just cheapened the whole ending, especially with the stuff leading up to it being surprisingly literal. I think this is probably why Alan Moore reffered to the script as juvinile, and had his name taken off of it. This is also were it started to stray mostly from the novel.
I didn't mind the rain scene, as it was a way to show the dynamic of V/Evey in the book: V a figure of vengeance burn of fire, Evey, a figure of love cleansed in the rain.
I too thought Evey should of been more desperate, like in the book, she came of as too strong, which didn't allow for teh dichotimy of the proson scene to have as much power. In the book, she ends up in the prison after failing an assassination attempt on (I think) McCready, wheich allows for an already broken figure to than go through the horro and trauma that V than lays on her in the prison sequence. It's more pathetic that way, and makes her acceptance of death more powerful. Still, a minor quible, with my big nit pick being the masks and the crowd scene, not for logistical reasons, but for the lazy cinematic reason.
I too would love for an Alan Moore commentary, as based on his interview, the man can talk. I'm not holding my breath though.