This was very good, if somewhat convoluted at times. The biggest hurdle for me was actually the art--it took me a while to get the swing of who was who, and once I did it went a lot smoother. I also think having seen the movie was a bit of a disadvantage, since the movie combined characters and took out a number of sub-plots, so I was a bit confused at times.
I loved the fact that V is such an ambiguous character--you never really get any clue what his story is, other than the bare minimum. I thought it was fantastic that he is neither a hero nor a villain, just somewhere in between. I've always enjoyed grey characters--characters you can't fit into "good" or "evil" categories.
I know I'll be shunned in some corners for admitting this, but I did prefer the movie over the source material. The graphic novel was a good read, but overall the movie captured everything that needed to be said without getting overly complex. Either way, I'm glad I read the graphic novel and I can definitely see how it has turned into a classic. I need to read more Alan Moore after this!